CN114566723A

CN114566723A - Electrolyte for rechargeable electrochemical cells

Info

Publication number: CN114566723A
Application number: CN202210199461.0A
Authority: CN
Inventors: G·W·艾登森; S·S·包尔斯; F·W·里奇
Original assignee: Eos Energy Storage LLC
Current assignee: Eos Energy Technology Holdings LLC
Priority date: 2014-10-06
Filing date: 2017-03-29
Publication date: 2022-05-31
Also published as: WO2016057457A2; TW201628235A; AU2015328339A1; CN109155444A; PH12018502096A1; SG11201702665XA; MX2018011726A; JP6929222B2; KR102514143B1; PH12017500568A1; US10276872B2; US10305111B2; MX2017004379A; CL2017000843A1; DK3204970T3; PH12017500582A1; CL2017000846A1; AU2015328274A1; IL251502A0; AU2017242009A1

Abstract

The present application relates to electrolytes for rechargeable electrochemical cells. One aspect of the invention provides an electrolyte for use in a bipolar static secondary zinc-bromine electrochemical cell comprising 25 to 70 wt% ZnBr₂5 to 50% by weight of water, 0.5 to 5% by weight of C_2‑10A glycol and 0.05% to 10% by weight of one or more quaternary ammonium agents.

Description

Electrolyte for rechargeable electrochemical cells

The present application is a divisional application of the invention patent application having an application date of 2017, 3 and 29, and an application number of "201780029813.5", entitled "electrolyte for rechargeable electrochemical cell".

Cross Reference to Related Applications

This PCT application claims the benefit of united states application No. 15/083,558 filed on 3, 29 of 2016. The documents are incorporated by reference herein in their entirety.

Technical Field

The present invention relates to electrolytes that can be used in zinc halide rechargeable electrochemical cells (e.g., energy storage batteries). More particularly, the invention relates to aqueous electrolytes for reversibly electrolyzing zinc halides in electrochemical energy storage cells or batteries.

Background

Zinc-halogen batteries are being developed as a means of storing electrical energy. Conventional zinc-halide batteries (e.g., zinc-bromine batteries) employ bipolar electrodes disposed in a static (i.e., non-flowing) aqueous solution of zinc bromide. The process of charging and discharging current in zinc-halogen batteries is usually carried out by zinc halide electrolytes like Zn²⁺Zn(s) and X^-/X₂Wherein X is a halogen (e.g., Cl, Br, or I).

When the battery is charged with electric current, the following chemical reactions occur:

Zn²⁺+2e^-→Zn

2X^-→X₂+2e^-。

in contrast, when the battery discharges current, the following chemical reactions occur:

Zn→Zn²⁺+2e^-

X₂+2e^-→2X^-。

in addition, in some batteries, polyhalide reactions can also occur. Some of these examples are described by:

or

For n.gtoreq.3.

The polyhalide reaction shown above can include the same halogen (e.g., Br)₃) And reactions between different halogens, e.g. mixed halogens, e.g. Br₂Cl。

These zinc-halogen energy storage batteries are typically configured in bipolar electrochemical batteries, with each electrode disposed in an aqueous zinc salt electrolyte. However, the performance of these energy storage batteries is due to dissolution in aqueous electrolytesSide reactions of the substance and high inefficiency. In solution, for example, elemental bromine is present as bromide ions at equilibrium to form polybromide ions,

wherein m is 3,5, or 7. When the electrolyte is formulated with excess free water, the side hydrolysis reaction is also problematic for these types of energy storage batteries because bromate solids form, which in turn reduces the amount of available bromide/bromine in the electrochemical cell that can be reduced or oxidized.

Elemental bromine also has an increased vapor pressure, which increases the harmful pressure in the battery. Furthermore, when aqueous zinc halide salts are ionized, zinc ions can be present as various complex ions and ion pairs, which promote zinc dendrite formation and increase the incidence of self-discharge in the battery. In order to improve the durability of an electrolyte in a secondary battery, a halogen separator (e.g., a quaternary ammonium salt or a heteroaryl salt (e.g., a pyridinium salt)) is added; however, these release agents typically have reduced solubility and reduced electrolyte stability over multiple charge cycles.

Disclosure of Invention

The present invention provides an aqueous electrolyte for use in a rechargeable zinc-halogen energy storage battery having improved stability and durability and improved zinc-halogen battery performance. In one aspect, the electrolyte comprises about 25 wt% to about 70 wt% ZnBr₂From about 5 wt% to about 50 wt% water, and one or more quaternary ammonium agents, wherein the electrolyte comprises from about 0.05 wt% to about 10 wt% of the one or more quaternary ammonium agents.

In some embodiments, the electrolyte further comprises at least one alkaline halogen salt selected from NaCl, NaBr, LiCl, LiBr, RbCl, RbBr, KCl, KBr, and the total concentration of alkaline halogen salts is from about 2 wt% to about 35 wt% by weight of the electrolyte. For example, the electrolyte further comprises about 1 wt% to about 15 wt% KBr, and about 5 wt% to about 20 wt% KCl.

In some embodiments, the electrolyte comprises about 27 wt% to about 40 wt% ZnBr₂. For example, the electrolyte comprises about 28 wt% to about 37 wt% ZnBr₂。

In some embodiments, the electrolyte comprises about 1.5 wt% to about 7.5 wt% ZnCl₂。

Also, in some embodiments, the electrolyte comprises from about 30 wt% to about 45 wt% water. For example, the electrolyte comprises about 35 wt% to about 41 wt% water.

In an alternative embodiment, the electrolyte comprises about 2 wt% to about 10 wt% KBr. For example, the electrolyte comprises about 7.3 wt% to about 9.2 wt% KBr.

And, in some embodiments, the electrolyte comprises about 7 wt% to about 17 wt% KCl.

In some embodiments, the electrolyte comprises about 0.5 wt% to about 10 wt% glyme. Also, in some embodiments, the glyme includes monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or any combination thereof. For example, the electrolyte comprises about 2 wt% to about 4 wt% tetraglyme.

In some embodiments, the electrolyte comprises from about 0.5 wt% to about 2.5 wt% of an ether selected from DME-PEG, dimethyl ether, or any combination thereof. For example, the electrolyte comprises DME-PEG, and the DME-PEG has an average molecular weight of about 350amu to about 3000 amu. In other examples, the DME-PEG has an average molecular weight of about 1200amu to about 3000 amu. Also, in some embodiments, the DME-PEG is DME-PEG2000, DME-PEG1000, or a combination thereof. In other examples, the electrolyte comprises about 1 wt% to about 2 wt% DME-PEG 2000. And, in some examples, the electrolyte comprises about 0.25 wt% to about 0.75 wt% DME-PEG 1000. For example, the electrolyte comprises from about 1 wt% to about 2 wt% DME-PEG2000 and from about 0.25 wt% to about 0.75 wt% DME-PEG 1000.

In some embodiments, the electrolyte further comprises about 0.1 wt% to about 1.0 wt% of an alcohol, wherein the alcohol is substantially miscible in water. For example, the alcohol includes C_1-4An alcohol. In other examples, the alcohol comprises methanol, ethanol, 1-propanol, isopropanol, 1-butanol, sec-butanol, isobutanol, tert-butanol, or any combination thereof. For example, the electrolyte comprises from about 0.25 wt.% to about 0.75 wt.% t-butanol.

In some embodiments, the electrolyte comprises about 0.5 wt% to about 5 wt% C_1-10A diol. In some examples, the diol comprises ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, hexanediol, or any combination thereof. And, in some embodiments, the electrolyte comprises from about 0.25 wt% to about 2.5 wt% neopentyl glycol.

In some embodiments, the electrolyte further comprises from about 0.05 wt% to about 20 wt% of one or more quaternary ammonium agents. And, in some examples, the one or more quaternary ammonium agents include a quaternary ammonium agent selected from the group consisting of: ammonium, tetraethylammonium, trimethylpropylammonium, N-methyl-N-ethylmorpholine (MEM), N-ethyl-N-methylmorpholine, N-methyl-N-butylmorpholine, N-methyl-N-ethylpyrrolidinium, N, N, N-triethyl-N-propylammonium, N-ethyl-N-propylpyrrolidinium, N-propyl-N-butylpyrrolidinium, N-methyl-N-butylpyrrolidinium, 1-methyl-1-butylpyrrolidinium, N-ethyl-N- (2-chloroethyl) pyrrolidinium, N-methyl-N-hexylpyrrolidinium, N-methyl-N-pentylpyrrolidinium, N-ethyl-N-pentylpyrrolidinium, N-ethyl-N-butylpyrrolidinium, trimethylene-bis (N-methylpyrrolidinium), N-butyl-N-pentylpyrrolidinium, N-methyl-N-propylpyrrolidinium, N-propyl-N-pentylpyrrolidinium, 1-ethyl-4-methylpyridinium, 1-ethyl-3-methylpyridinium, 1-ethyl-2-methylpyridinium, 1-butyl-3-methylpyridinium, cetyltrimethylammonium, triethylmethylammonium chloride or bromide, and any combination thereof. In some examples, the quaternary ammonium agent comprises chloride or bromide of 1-ethyl-4-methylpyridinium, 1-ethyl-2-methylpyridinium, 1-ethyl-3-methylpyridinium, triethylmethylammonium, 1 '-dioctadecyl-4-4' -bipyridinium, or any combination thereof. In some examples, the one or more quaternary ammonium agents include a quaternary ammonium agent selected from the group consisting of: chloride or bromide of ammonium, tetraethylammonium, trimethylpropylammonium, N-methyl-N-ethylmorpholine (MEM), 1-ethyl-1-methylmorpholine, N-methyl-N-ethylpyrrolidinium, 1-methyl-1-butylpyrrolidinium, 1-ethyl-4-methylpyridinium, 1-ethyl-2-methylpyridinium, 1-butyl-3 methylpyridinium, hexadecyltrimethylammonium, triethylmethylammonium, and any combination thereof.

In some embodiments, the electrolyte further comprises from about 0.05 wt% to about 20 wt% of one or more quaternary ammonium agents, and the one or more quaternary ammonium agents comprise a quaternary ammonium agent selected from the group consisting of: ammonium bromide, ammonium chloride, tetraethylammonium bromide, trimethylpropylammonium bromide, N-methyl-N-ethylmorpholinium bromide (MEMBr), N-methyl-N-butylmorpholinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N, N, N-triethyl-N-propylammonium bromide, N-ethyl-N-propylpyrrolidinium bromide, N-propyl-N-butylpyrrolidinium bromide, N-methyl-N-butylpyrrolidinium bromide, 1-methyl-1-butylpyrrolidinium bromide, N-ethyl-N- (2-chloroethyl) pyrrolidinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N-ethyl-N- (2-chloroethyl) pyrrolidinium bromide, N-ethylpyrrolidinium bromide, N-ethylpyrrolidinium bromide, N-ethylpyrroli, N-methyl-N-hexylpyrrolidinium bromide, N-methyl-N-pentylpyrrolidinium bromide, N-ethyl-N-butylpyrrolidinium bromide, trimethylene-bis (N-methylpyrrolidinium) dibromide, N-butyl-N-pentylpyrrolidinium bromide, N-methyl-N-propylpyrrolidinium bromide, N-propyl-N-pentylpyrrolidinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, cetyltrimethylammonium bromide, cetylpyridinium bromide, and mixtures thereof, Triethylmethylammonium bromide, and any combination thereof. In some examples, the quaternary ammonium agent includes at least one of 1-ethyl-4-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, triethylmethylammonium chloride, 1 '-dioctadecyl-4-4' -bipyridinium dibromide, or 1-ethyl-4-methylpyridinium bromide. In some examples, the one or more quaternary ammonium agents include a quaternary ammonium agent selected from the group consisting of: ammonium chloride, tetraethylammonium bromide, trimethylpropylammonium bromide, N-methyl-N-ethylmorpholinium bromide (MEMBr), N-methyl-N-ethylpyrrolidinium bromide, 1-methyl-1-butylpyrrolidinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-ethyl-2 methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, hexadecyltrimethylammonium bromide, decyltrimethylammonium bromide, tridecyltrimethylammonium bromide, or any combination thereof.

In some embodiments, the one or more quaternary ammonium agents include at least one agent selected from 1-ethyl-2-methylpyridinium bromide, 1-ethyl-3-methylpyridinium bromide, or 1-ethyl-4-methylpyridinium bromide.

In some embodiments, the one or more quaternary ammonium agents comprise from about 3.5 wt% to about 4.5 wt% of 1-ethyl-2-methylpyridinium bromide, 1-ethyl-3-methylpyridinium bromide, or 1-ethyl-4-methylpyridinium bromide, by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise from about 1 wt% to about 7 wt% of 1-ethyl-2-methylpyridinium bromide, by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise from about 1.5 wt% to about 2.5 wt% 1-methyl-1-butylpyrrolidinium bromide, by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise from about 1.5 wt% to about 2.5 wt% 1-butyl-3-methylpyridinium bromide, by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise from about 1.5 wt% to about 5 wt% of 1-methyl-1-ethylmorpholine bromide, by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise about 0.5 wt% to about 1.5 wt% N-methyl-N-ethylmorpholine bromide (MEMBr), by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise from about 14.5 wt% to about 16.5 wt% N-methyl-N-ethylpyrrolidinium bromide, by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise from about 2 wt% to about 3 wt% trimethylpropylammonium bromide, by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise from about 2 wt% to about 8 wt% tetraethylammonium bromide, by weight of the electrolyte. In some embodiments, the one or more quaternary ammonium agents comprise from about 0.05 wt% to about 0.2 wt% cetyltrimethylammonium bromide, by weight of the electrolyte.

And, In other embodiments, the electrolyte comprises less than 1 wt% of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, or Fe, by weight of the electrolyte. For example, the one or more additives are selected from about 0.0008 wt% to about 0.0012 wt% Sn (e.g., as SnCl)₂Or any hydrate thereof), from about 0.0008 wt% to about 0.0012 wt% In (e.g., as InCl)₃Or any hydrate thereof), and combinations thereof.

In some embodiments, the electrolyte comprises an acid or a conjugate base of an acid selected from the group consisting of acetic acid, nitric acid, hydrobromic acid, and citric acid. For example, the electrolyte comprises from about 0.3 wt% to about 0.6 wt% acetic acid, sodium acetate, or potassium acetate, by weight of the electrolyte. In another example, the electrolyte comprises from about 0.12 wt% to about 0.08 wt% nitric acid, by weight of the electrolyte. And, in some examples, the electrolyte comprises about 3.5 wt% to about 4.5 wt% citric acid by weight of the electrolyte. In an alternative example, the electrolyte comprises from about 3.5 wt% to about 4.5 wt% monopotassium citrate, by weight of the electrolyte.

In other embodiments, the electrolyte comprises from about 0.05 wt% to about 0.75 wt% of a crown ether (e.g., 18

crown

6, 15

crown

5, 12 crown 4, or any combination thereof) by weight of the electrolyte. In some embodiments, the choice of corona is dependent on the cation formed by the dissolution of the alkaline halide salt in the electrolyte. For example, where one or more of the alkaline halogen salts form Li in the electrolyte⁺A cation, the electrolyte comprising from about 0.05 wt% to about 0.75 wt% of 12 crown 4 ether. Also for example, wherein one or more of the alkaline halide salts form Na in the electrolyte⁺A cation, the electrolyteComprising from about 0.05% to about 0.75% by weight of 15 crown 5 ether. And, in some examples, wherein one or more of the alkaline halide salts form K in the electrolyte⁺A cation, the electrolyte comprising from about 0.05 wt% to about 0.75 wt% of 18 crown 6 ether. In some examples, the electrolyte comprises about 0.15 wt% to about 0.5 wt% of 18-crown-6 by weight of the electrolyte. In other examples, the electrolyte comprises from about 0.05 wt% to about 0.2 wt% of 15-crown-5, by weight of the electrolyte.

Another aspect of the invention provides an electrolyte for use in a secondary zinc halide electrochemical cell comprising about 27 wt% to about 40 wt% ZnBr, by weight of the electrolyte₂About 35 wt% to about 41 wt% water, about 7.3 wt% to about 9.2 wt% KBr, about 7 wt% to about 17 wt% KCl, about 0.3 wt% to about 0.6 wt% acetic acid, and about 2 wt% to about 8 wt% tetraethylammonium bromide, wherein these weight percentages are by weight of the electrolyte.

Another aspect of the invention provides an electrolyte for use in a secondary zinc halide electrochemical cell comprising about 27 wt% to about 40 wt% ZnBr, by weight of the electrolyte₂And from about 1% to about 10% by weight of 1-ethyl-4-methylpyridinium bromide or from about 1% to about 7% by weight of 1-ethyl-2-methylpyridinium bromide.

Another aspect of the invention provides an electrolyte for use in a secondary zinc halide electrochemical cell comprising about 27 wt% to about 40 wt% ZnBr, by weight of the electrolyte₂And about 5ppm to about 15ppm In, Sn, or both. In some embodiments, the electrolyte further comprises 1-ethyl-4-methylpyridinium bromide.

In some embodiments, the electrolyte further comprises cetyl trimethylammonium bromide (CTAB) in an amount of about 0.05 wt% to about 0.2 wt%, by weight of the electrolyte.

In some embodiments, the electrolyte comprises from about 3.5% to about 4.5% citric acid monohydrate by weight of the electrolyte.

In some embodiments, the electrolyte comprises from about 3.5% to about 4.5% by weight of the electrolyte of potassium dihydrogen citrate monohydrate.

Another aspect of the invention provides an electrolyte for use in a secondary zinc halide electrochemical cell comprising about 27 wt% to about 40 wt% ZnBr, by weight of the electrolyte₂About 35 to about 41 weight percent water, about 7.3 to about 9.2 weight percent KBr, about 7 to about 17 weight percent KCl, about 0.15 to about 0.5 weight percent 18-crown-6, and about 0.05 to about 0.2 weight percent cetyltrimethylammonium bromide, wherein weight percentages are by weight of the electrolyte.

In some embodiments, the electrolyte comprises from about 2 wt% to about 8 wt% tetraethylammonium bromide, by weight of the electrolyte.

In some embodiments, the electrolyte comprises from about 0.3 wt% to about 0.6 wt% acetic acid, by weight of the electrolyte. In some examples, the electrolyte comprises from about 0.3 wt% to about 0.6 wt% HBr, by weight of the electrolyte.

In some embodiments, the electrolyte comprises about 1 wt% to about 2 wt% DME-PEG2000 (MEPG 2K). In some embodiments, the electrolyte comprises about 0.25 wt% to about 0.75 wt% DME-PEG1000 (MEPG 1K). In other embodiments, the electrolyte further comprises about 1 wt% to about 2 wt% DME-PEG2000 (MPEG2K) and about 0.25 wt% to about 0.75 wt% DME-PEG1000 (MPEG 1K).

In another aspect of the invention, there is provided a method of preparing an electrolyte for use in a secondary zinc halide electrochemical cell comprising mixing ZnBr under aqueous conditions₂KBr, KCl, and one or more quaternary ammonium agents to produce a mixture and stirring the mixture until the solids have dissolved or are uniformly distributed throughout the mixture, wherein the mixture comprises about 27 wt% to about 40 wt% ZnBr₂About 7.3 wt% to about 9.2 wt% KBr, about 7 wt% to about 17 wt% KCl, about 0.05 wt% to about 20 wt% of one or more quaternary ammonium agents, and about 35 wt% to about 41 wt%% of water.

Another aspect of the invention provides an electrolyte for use in a secondary static zinc halide electrochemical cell comprising a polymeric concentration of one or more quaternary ammonium agents from about 2.0 wt% to about 15.0 wt%, wherein the one or more quaternary ammonium agents comprises at least cetyltrimethylammonium chloride or cetyltrimethylammonium bromide.

In some embodiments, the electrolyte further comprises about 0.2 wt% to about 1.2 wt% cetyltrimethylammonium chloride or bromide, and at least one additional quaternary ammonium agent. For example, the electrolyte additionally comprises alkyl-substituted pyridinium chloride or alkyl-substituted pyridinium bromide. In some examples, the electrolyte comprises from about 1.8 wt% to about 7.5 wt% of the alkyl-substituted pyridinium chloride or alkyl-substituted pyridinium bromide. In other examples, the electrolyte comprises from about 2.0 wt% to about 6.0 wt% of the alkyl-substituted pyridinium chloride or alkyl-substituted pyridinium bromide. For example, the electrolyte comprises from about 2.0 wt% to about 6.0 wt% of an alkyl-substituted pyridinium bromide, wherein the alkyl-substituted pyridinium bromide is selected from the group consisting of 1-ethyl-2-methylpyridinium bromide, 1-ethyl-3-methylpyridinium bromide, and 1-ethyl-4-methylpyridinium bromide.

In some embodiments, the electrolyte comprises from about 0.05% to about 0.2% by weight of 1,1 '-dioctadecyl-4-4' -bipyridinium chloride or from about 0.05% to about 0.2% by weight of 1,1 '-dioctadecyl-4-4' -bipyridinium bromide.

In some embodiments, the electrolyte further comprises about 25 wt% to about 40 wt% ZnBr₂. In some embodiments, the additional electrolyte comprises about 25 wt.% to about 45 wt.% water. In some embodiments, the electrolyte further comprises about 1 wt% to about 5 wt% KBr. And, in some embodiments, the electrolyte further comprises from about 5 wt% to about 15 wt% KCl.

In some embodiments, the electrolyte comprises from about 0.5 wt% to about 2.5 wt% of an ether selected from DME-PEG, dimethyl ether, or any combination thereof. In some examples, the ether is DME-PEG, and the DME-PEG has an average molecular weight of about 350amu to about 3000 amu. For example, DME-PEG has an average molecular weight of about 750amu to about 2500 amu. In some embodiments, the ether is DME-PEG, and the electrolyte comprises from about 0.1 wt% to about 0.5 wt% DME-PEG having an average molecular weight of from about 750amu to about 1250 amu. In some embodiments, the ether is DME-PEG, and the electrolyte comprises from about 1.0 wt% to about 2.0 wt% DME-PEG having an average molecular weight of 1750amu to about 2250 amu.

In some embodiments, the electrolyte further comprises from about 2 wt% to about 6 wt% tetraethylammonium chloride or tetraethylammonium bromide. For example, the electrolyte comprises about 2 wt% to about 6 wt% tetraethylammonium bromide.

In some embodiments, the electrolyte further comprises N-ethyl-N-methylmorpholine chloride or N-ethyl-N-methylmorpholine bromide. For example, the electrolyte comprises from about 0.5 wt% to about 2.0 wt% of N-ethyl-N-methylmorpholine chloride or N-ethyl-N-methylmorpholine bromide.

Another aspect of the invention provides an electrolyte for use in a secondary zinc-bromine electrochemical cell comprising about 25 wt.% to about 40 wt.% ZnBr₂About 25 wt% to about 45 wt% water, and one or more quaternary ammonium agents, wherein the electrolyte has a polymerization concentration of the one or more quaternary ammonium agents of about 2.0 wt% to about 15.0 wt%, and wherein the one or more quaternary ammonium agents comprises at least cetyl trimethylammonium bromide, and an alkyl-substituted pyridinium bromide, wherein the alkyl-substituted pyridinium bromide is selected from 1-ethyl-2-methylpyridinium bromide, 1-ethyl-3-methylpyridinium bromide, or 1-ethyl-4-methylpyridinium bromide.

In some embodiments, the electrolyte further comprises about 0.2 wt% to about 1.2 wt% cetyltrimethylammonium bromide and about 1.8 wt% to about 7.5 wt% alkyl-substituted pyridinium bromide.

In some embodiments, the electrolyte further comprises from about 0.05% to about 0.2% by weight of 1,1 '-dioctadecyl-4-4' -bipyridinium chloride or from about 0.05% to about 0.2% by weight of 1,1 '-dioctadecyl-4-4' -bipyridinium bromide.

In some embodiments, the electrolyte further comprises about 1 wt% to about 5 wt% KBr. In some embodiments, the electrolyte further comprises from about 5 wt% to about 15 wt% KCl.

Another aspect of the invention provides an electrolyte for use in a secondary zinc-bromine electrochemical cell comprising about 25 wt.% to about 40 wt.% ZnBr₂About 25 wt% to about 45 wt% water, and one or more quaternary ammonium agents, wherein the electrolyte has a polymerization concentration of the one or more quaternary ammonium agents of about 2.0 wt% to about 15.0 wt%, and wherein the one or more quaternary ammonium agents comprises at least cetyltrimethylammonium bromide, and tetraethylammonium bromide.

In some embodiments, the electrolyte comprises about 0.2 wt% to about 1.2 wt% cetyltrimethylammonium bromide and about 2.0 wt% to about 6.0 wt% tetraethylammonium bromide.

In some embodiments, the electrolyte further comprises from about 0.5 wt% to about 2.0 wt% of N-ethyl-N-methylmorpholine chloride or N-ethyl-N-methylmorpholine bromide.

In some embodiments, the electrolyte comprises about 1 wt% to about 5 wt% KBr. In some embodiments, the electrolyte comprises from about 5 wt% to about 15 wt% KCl.

In some embodiments, the electrolyte comprises about 1.0 wt% to about 5 wt% glyme, wherein the ether is selected from diglyme, triglyme, or tetraglyme.

Another aspect of the invention provides an electrolyte for use in a secondary zinc-bromine electrochemical cell comprising from about 1.0 wt% to about 5 wt% of a tetra-alkyl ammonium chloride, from about 25 wt% to about 40 wt% of ZnBr₂And from about 25 wt% to about 45 wt% water.

In some embodiments, the tetra-alkyl ammonium chloride is (C)_1-6Alkyl radical)₄N⁺Cl^-. In other embodiments, tetra-alkylThe ammonium chloride is selected from triethylmethylammonium chloride, triethylpropylammonium chloride, butyltrimethylammonium chloride, tetraethylammonium chloride, trimethylethylammonium chloride, or any combination thereof. For example, the tetra-alkyl ammonium chloride is triethylmethylammonium chloride.

In some embodiments, the electrolyte comprises cetyltrimethylammonium bromide or cetyltrimethylammonium chloride.

In some embodiments, the electrolyte comprises tetraethylammonium bromide or tetraethylammonium chloride.

In some embodiments, the electrolyte comprises about 0.2 wt% to about 1.2 wt% cetyltrimethylammonium bromide and about 1.5 wt% to about 5.0 wt% tetraethylammonium bromide.

In some embodiments, the electrolyte comprises from about 0.5 wt% to about 2.0 wt% of N-ethyl-N-methylmorpholine chloride or N-ethyl-N-methylmorpholine bromide.

In some embodiments, the electrolyte comprises about 2.5 wt% to about 7.5 wt% KBr.

In some embodiments, the electrolyte comprises about 5 wt% to about 15 wt% KCl.

In some embodiments, the electrolyte comprises from about 0.1 wt% to about 0.5 wt% of DME-PEG having an average molecular weight of from about 750amu to about 1250 amu.

In some embodiments, the electrolyte comprises from about 1.0 wt% to about 2.0 wt% of DME-PEG having an average molecular weight of from about 1750amu to about 2250 amu.

In some embodiments, the electrolyte comprises an acid or a conjugate base of an acid selected from acetic acid, nitric acid, and citric acid. For example, the electrolyte comprises from about 0.1 wt% to about 1.0 wt% glacial acetic acid or from about 0.1 wt% to about 1.0 wt% HBr.

Another aspect of the invention provides an electrolyte for use in a secondary static zinc halide electrochemical cell comprising: about 30.00 wt% to about 50.00 wt% (e.g., about 35 wt% to about 47.5 wt% or about 37 wt% to about 46 wt%) ZnBr₂About 22.5 wt% to about 40 wt% (e.g., about 23.75 wt% to about 40 wt%)About 38 wt.% or about 24 wt.% to about 36 wt.%) of H₂O, about 3.00 wt% to about 9.5 wt% (e.g., about 4.00 wt% to about 8.5 wt%, about 3.00 wt% to about 8.5 wt%, or about 4.1 wt% to about 8 wt%) KBr, about 7.75 wt% to about 14.00 wt% (e.g., about 7.9 wt% to about 13.25 wt% or about 8 wt% to about 13 wt%) KCl, about 0.25 wt% to about 2.25 wt% (e.g., about 0.35 wt% to about 2.0 wt% or about 0.5 wt% to about 2 wt%) MPEG2K, and about 0.075 wt% to about 1.25 wt% (e.g., about 0.1 wt% to about 1 wt%) MPEG 1K.

In some embodiments, the electrolyte further comprises at least two different quaternary ammonium agents, wherein both quaternary ammonium agents are of formula N⁺(R^A)(R^B)₃X^-Is represented by the formula (I) in which R^AIs C_1-6Alkyl radical, R^BIs C_1-6Alkyl radical, and X^-Is Br^-Or Cl^-(ii) a And wherein the aggregate concentration of the at least two different quaternary ammonium agents is from about 3.50 wt% to about 20.00 wt%. In some examples, one of the at least two different quaternary ammonium agents is tetraethylammonium bromide and the tetraethylammonium bromide has a concentration of from about 0.35 wt% to about 3.75 wt%. In other examples, one of the at least two different quaternary ammonium agents is triethylmethylammonium chloride, and the triethylmethylammonium chloride has a concentration of from about 3.50 wt% to about 15.0 wt%.

In some embodiments, the electrolyte further comprises a quaternary ammonium agent selected from trimethyl propyl ammonium bromide, and the trimethyl propyl ammonium bromide has a concentration of about 0.25 wt% to about 0.75 wt%.

In some embodiments, the electrolyte further comprises from about 0.35 wt% to about 2.75 wt% of a diol, wherein the diol is selected from ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, hexanediol, or any combination thereof. For example, the electrolyte comprises from about 0.35 wt% to about 2.75 wt% neopentyl glycol.

In some embodiments, the electrolyte further comprises about 2.00 wt% to about 4.00 wt% of a glyme, wherein the glyme is selected from the group consisting of monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or any combination thereof. For example, the electrolyte further comprises about 2.00 wt% to about 4.00 wt% tetraglyme.

Another embodiment of the invention provides an electrolyte for use in a secondary static zinc halide electrochemical cell comprising about 30.00 wt.% to about 50.00 wt.% (e.g., about 35 wt.% to about 47.5 wt.% or about 37 wt.% to about 46 wt.%) ZnBr₂About 22.5% to about 40% (e.g., about 23.75% to about 38% or about 24% to about 36%) by weight of H₂O, about 3.00 wt% to about 9.5 wt% (e.g., about 4.00 wt% to about 8.5 wt%, about 3.00 wt% to about 8.5 wt%, or about 4.1 wt% to about 8 wt%) KBr, about 7.75 wt% to about 14.00 wt% (e.g., about 7.9 wt% to about 13.25 wt% or about 8 wt% to about 13 wt%) KCl, about 0.25 wt% to about 2.25 wt% (e.g., about 0.35 wt% to about 2.0 wt% or about 0.5 wt% to about 2 wt%) MPEG2K, about 0.075 wt% to about 1.25 wt% (e.g., about 0.1 wt% to about 1 wt%) MPEG 1K, and about 0.50 wt% to about 3.50 wt% of a first quaternary ammonium agent, wherein the first quaternary ammonium agent is selected from tetra-C_1-6Alkyl ammonium chlorides or tetra-C_1-6Alkyl ammonium bromides.

In some embodiments, the first quaternary ammonium agent is selected from tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, or tetrabutylammonium bromide.

In some embodiments, the electrolyte further comprises a second quaternary ammonium agent, wherein the second quaternary ammonium agent has the formula N⁺(R^A)(R^B)₃X^-Wherein R is^AIs C_1-6Alkyl radical, R^BIs different from R^AC of (A)_1-6Alkyl radical, and X^-Is Br^-Or Cl^-(ii) a And wherein the concentration of the second quaternary ammonium agent is from about 3.50 wt% to about 15.00 wt%. For example, the second quaternary ammonium agent is selected from the chlorides or bromides of trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium, or tripropylbutylammonium.

In some embodiments, the electrolyte further comprises a third quaternary ammonium agent, wherein the third quaternary ammonium agent has the formula N⁺(R^A)(R^B)₃X^-Wherein R is^AIs C_1-6Alkyl radical, R^BIs different from R^AC of (A)_1-6Alkyl radical, and X^-Is Br^-Or Cl^-(ii) a The third quaternary ammonium agent is different from the second quaternary ammonium agent, and wherein the concentration of the third quaternary ammonium agent is from about 0.25 wt% to about 0.85 wt%. In some examples, the third quaternary ammonium agent is selected from: trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium or tripropylbutylammonium chlorides or bromides.

In some embodiments, the electrolyte further comprises from about 0.35 wt% to about 2.75 wt% (e.g., from about 0.4 wt% to about 2.65 wt% or from about 0.5 wt% to about 2.5 wt%) of a diol, wherein the diol is selected from ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, hexylene glycol, or any combination thereof. For example, the electrolyte further comprises from about 0.35 wt.% to about 2.75 wt.% (e.g., from about 0.4 wt.% to about 2.65 wt.% or from about 0.5 wt.% to about 2.5 wt.%) neopentyl glycol.

Another aspect of the invention provides an electrolyte for use in a secondary static zinc halide electrochemical cell comprising: about 30.00 wt% to about 50.00 wt% (e.g., about 35 wt% to about 47.5 wt% or about 37 wt% to about 46 wt%) ZnBr₂About 22.5 wt.% to about 40 wt.% (e.g., about 23.75 wt.% to about 38 wt.% or about 24 wt.% to about 36 wt.%) of H₂O, about 3.00 wt% to about 9.5 wt% (e.g., about 4.00 wt% to about 8.5 wt%, about 3.00 wt% to about 8.5 wt%, or about 4.1 wt% to about 8 wt%) KBr, about 7.75 wt% to about 14.00 wt% (e.g., about 7.9 wt% to about 13.25 wt% or about 8 wt% to about 13 wt%) KCl, about 0.25 wt% to about 2.25 wt% (e.g., about 0.35 wt% to about 2.0 wt% or about 0.5 wt% to about 2 wt%) MPEG2K, about 0.075 wt% to about 1.25 wt% (e.g., about 0.1 wt% to about 1 wt%) MPEG 1K, and one or more quaternary ammonium agents, wherein each quaternary ammonium agent is independently selected from the group consisting of MPEG2K having the formula N⁺(R^A)(R^B)₃X^-In which R is^AIs C_1-6Alkyl radical, R^BIs C_1-6Alkyl radical, and X^-Is Br^-Or Cl^-(ii) a And wherein the one or more quaternary ammonium agents have an aggregate concentration of about 3.50 wt% to about 20.00 wt%.

In some embodiments, the electrolyte further comprises about 0.50 wt% to about 3.50 wt% of a first quaternary ammonium agent, wherein the first quaternary ammonium agent is selected from tetra-C_1-6Alkyl ammonium chlorides or tetra-C_1-6Alkyl ammonium bromides. For example, the first quaternary ammonium agent is selected from tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, or tetrabutylammonium bromide.

In some embodiments, the electrolyte further comprises a second quaternary ammonium agent, wherein the second quaternary ammonium agent has the formula N⁺(R^A)(R^B)₃X^-Wherein R is^AIs C_1-6Alkyl radical, R^BIs different from R^AC of (A)_1-6Alkyl radical, and X^-Is Br^-Or Cl^-(ii) a And wherein the concentration of the second quaternary ammonium agent is from about 3.50 wt% to about 15.00 wt%. In some examples, the second quaternary ammonium agent is selected from the chlorides or bromides of trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium, or tripropylbutylammonium. For example, the second quaternary ammonium agent is triethylmethylammonium chloride or triethylmethylammonium bromide.

In some embodiments, the electrolyte further comprises a third quaternary ammonium agent, wherein the third quaternary ammonium agent has the formula N⁺(R^A)(R^B)₃X^-Wherein R is^AIs C_1-6Alkyl radical, R^BIs different from R^AC of (A)_1-6Alkyl radical, and X^-Is Br^-Or Cl^-(ii) a The third quaternary ammonium agent is different from the second quaternary ammonium agent, and wherein the concentration of the third quaternary ammonium agent is from about 0.25 wt% to about 0.85 wt%. In some examples, the third quaternary ammonium agent is selected from the chlorides or bromides of trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium, or tripropylbutylammonium.

Another aspect of the invention provides an electrolyte for use in a secondary static zinc halide electrochemical cell comprising about 30.00 wt.% to about 50.00 wt.% (e.g., about 35 wt.% to about 47.5 wt.% or about 37 wt.% to about 46 wt.%) ZnBr₂About 22.5 wt.% to about 40 wt.% (e.g., about 23.75 wt.% to about 38 wt.% or about 24 wt.% to about 36 wt.%) of H₂O, about 3.00 wt% to about 9.5 wt% (e.g., about 4.00 wt% to about 8.5 wt%, about 3.00 wt% to about 8.5 wt%, or about 4.1 wt% to about 8 wt%) KBr, about 7.75 wt% to about 14.00 wt% (e.g., about 7.9 wt% to about 13.25 wt% or about 8 wt% to about 13 wt%) KCl, about 0.25 wt% to about 2.25 wt% (e.g., about 0.35 wt% to about 2.0 wt% or about 0.5 wt% to about 2 wt%) MPEG2K, about 0.075 wt% to about 1.25 wt% (e.g., about 0.1 wt% to about 1 wt%) MPEG 1K, about 3.50 wt% to about 15.00 wt% chloride or bromide of triethylmethylammonium, and about 0.50 wt% to about 3.50 wt% tetra-C_1-6Chlorides or bromides of alkylammonium.

In some embodiments, the electrolyte further comprises from about 0.25 wt% to about 0.75 wt% of a polymer having the formula N⁺(R^A)(R^B)₃X^-In which R is^AIs C_1-6Alkyl radical, R^BIs different from R^AC of (A)_1-6Alkyl radical, and X^-Is Br^-Or Cl^-(ii) a And the alkylammonium agent is not the chloride or bromide of triethylmethylammonium. For example, the quaternary ammonium agent is selected from the chlorides or bromides of trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium, or tripropylbutylammonium.

In some embodiments, the electrolyte further comprises about 0.35 wt% to about 2.75 wt% (e.g., about 0.4 wt% to about 2.65 wt% or about 0.5 wt% to about 2.5 wt%) of a diol, wherein the diol is selected from the group consisting of ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, hexylene glycol, or any combination thereof. For example, the electrolyte further comprises from about 0.35 wt.% to about 2.75 wt.% (e.g., from about 0.4 wt.% to about 2.65 wt.% or from about 0.5 wt.% to about 2.5 wt.%) neopentyl glycol.

Drawings

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings.

Fig. 1 shows an exploded view of an electrochemical cell according to an embodiment of the present invention.

Fig. 2A and 2B are front and side views, respectively, of a bipolar electrode according to an embodiment of the present invention.

FIG. 3 shows an exploded view of a bipolar electrode according to an embodiment of the invention.

FIG. 4A shows a front view of a bipolar electrode according to an embodiment of the invention.

Figure 4B illustrates an exploded view of a bipolar electrode according to an embodiment of the present invention.

Fig. 5 illustrates a view of the back surface of an electrode plate having a grit blasted area in accordance with an embodiment of the invention.

Fig. 6A and 6B show a front view and a side view, respectively, of a cathode holder according to an embodiment of the present invention.

Fig. 7A and 7B show a front view of a cathode holder and an enlarged view of a cathode holder material having a hole therethrough, respectively, according to an embodiment of the invention.

Fig. 8 illustrates a cross-sectional view of a portion of an electrochemical cell having an interface between a front surface of a bipolar electrode plate (including a cathode assembly mounted thereon) and a back surface of a second electrode plate or an inner surface of a terminal end plate according to an embodiment of the present invention.

FIG. 9 illustrates front, side, and top perspective views of a carbon material for use as a cathode according to an embodiment of the present invention.

Fig. 10 shows experimental data of a spacing between three-dimensional shape profiles of a bipolar electrode plate and a cathode holder according to an embodiment of the present invention with respect to Z-axis and X-axis.

Fig. 11 shows experimental data on the spacing between the three-dimensional shape profiles of the bipolar electrode plate and the cathode according to an embodiment of the present invention with respect to the Z-axis and the X-axis.

Fig. 12 shows a perspective view of a terminal assembly according to an embodiment of the invention.

Fig. 13 illustrates a top perspective view of a terminal assembly for a bipolar battery according to an embodiment of the present invention, including a terminal end plate and an electrically conductive cup-shaped member having a generally oval-shaped edge joined to the end plate.

Fig. 14 shows a top view of an end plate of the terminal assembly of fig. 13 having an electrochemically active area including a first surface area surrounded by an edge of an electrically conductive cup-shaped member and a remaining second surface defined by an outer perimeter of the edge and a peripheral edge of the electrochemically active area, in accordance with an embodiment of the present invention.

Fig. 15 is a cross-sectional view taken along line 17-17 of fig. 13, illustrating the conductive cup-shaped member and the remaining second surface defined by the outer periphery of the rim and the peripheral edge of the electrochemically active area, in accordance with an embodiment of the present invention.

Fig. 16 is a top perspective view of the terminal assembly of fig. 13 showing a bipolar endplate and a conductive cup-shaped member including a generally circular rim in accordance with an embodiment of the present invention.

Fig. 17 is a cross-sectional view taken along line 15-15 of fig. 13, illustrating the terminal assembly further including a frame member opposite a second surface of the end plate received on a side opposite the conductive cup member in accordance with an embodiment of the present invention.

Fig. 18 is a side view of a battery pack including a cathode terminal and an anode terminal with bipolar electrodes and a frame member between compression plates according to an embodiment of the invention.

Fig. 19 is a top perspective view of a battery pack according to an embodiment of the invention, including a pair of terminal assemblies at respective proximal and distal ends of the battery modules.

Fig. 20 is an exploded view of the battery pack of fig. 18 according to an embodiment of the present invention.

Fig. 21 shows a front view of a seal for use in the battery module of fig. 20 and a cross-sectional view of the seal.

Fig. 22 illustrates a top perspective view of a press plate for the cathode and anode terminals of the battery pack of fig. 18, according to an embodiment of the present invention.

Fig. 23 illustrates a front view and a side view of a frame for use in the battery pack of fig. 18, according to an embodiment of the present invention.

Fig. 24 shows representative behavior in terms of discharge energy over several charge cycles for a battery pack according to an embodiment of the invention.

Fig. 25A and 25B show representative behaviors of the battery module according to the embodiment of the present invention. Fig. 25A shows the operating time of the battery with respect to the average discharge power. Fig. 25B shows the energy efficiency of the battery with respect to the average discharge power.

Fig. 26 shows a representative behavior of the battery module according to the embodiment of the present invention in terms of discharge energy with respect to average discharge power.

Fig. 27A and 27B show representative behaviors of the battery module according to the embodiment of the present invention. Fig. 27A shows the energy efficiency of the battery over several discharge cycles. Fig. 27B shows the discharge run time of the battery after several discharge cycles.

Fig. 28 shows representative behavior of electrolytes according to embodiments of the present invention in terms of a plot of energy as a function of charge cycle in a test cell employing an electrolyte of the present invention and electrolytes reported in the open literature.

Fig. 29A shows representative behavior of electrolytes according to embodiments of the present invention in terms of capacity as a function of charge cycle in test cells employing the electrolytes of the present invention and electrolytes reported in the open literature.

Fig. 29B shows representative behavior of electrolytes according to embodiments of the present invention as a function of charge cycle in a test cell employing an electrolyte of the present invention and electrolytes reported in the open literature.

Fig. 30A and 30B are photographs of zinc metal plated on the rear surface of an electrode plate, wherein the corresponding cathode holder has an unadjusted hole pattern.

Fig. 31A, 31B and 31C are photographs of zinc metal plated on the rear surface of an electrode plate, in which the corresponding cathode holder has an adjusted hole pattern.

FIG. 32 is a graph of power (at Br) as a function of stability (change in pH after 7 days at 60 ℃)₂Maximum power at reduced limiting current) shows representative behavior of various bromine complexing agents.

FIG. 33 shows a comparison of bromine activity of various ethylpicolines in terms of logarithmic current as a function of voltage.

FIG. 34 is a graph of power (at Br) as a function of stability (change in pH after 7 days at 60 ℃)₂Maximum power at reduced limiting current) shows a comparison of different polyethers of the bromine complexing agent.

Fig. 35 is a graph of discharge capacity (mAh) versus charge cycle number for an electrochemical cell of the present invention assembled to include the electrolyte formulation exemplified by example No. 1.

Fig. 36 is a graph of coulombic efficiency (%) versus number of charge cycles for an electrochemical cell of the invention assembled to comprise the electrolyte formulation of example No. 1.

Fig. 37 is a graph of run time (hours) versus charge cycle number for an electrochemical cell of the present invention assembled to contain the electrolyte formulation of example No. 1.

Fig. 38 is a graph of energy efficiency (%) versus charge cycle number for an electrochemical cell of the present invention assembled to comprise the electrolyte formulation of example No. 1.

Fig. 39 shows a graph of cyclic voltammetry measurements for a battery pack of the invention assembled to contain an electrolyte formulation of example No. 5.

FIG. 40 is an exploded view of a test cell according to an embodiment of the present invention and described in example 6A

Fig. 41 is a top view of a test cell according to an embodiment of the present invention and described in example 6A.

Fig. 42 is a perspective view of a test cell according to an embodiment of the present invention and described in example 6A.

Fig. 43 is a top view of a housing and reaction chamber of a test cell according to an embodiment of the present invention and described in example 6A.

Fig. 44 shows a graph of energy and coulombic efficiency for the test cells according to example 6A.

Fig. 45 shows a graph of energy and coulombic efficiency for the test cell according to example 6B.

Fig. 46 shows a graph of a tafel plot of ethylpicoline according to example 6B.

Fig. 47 shows a graph of energy efficiency versus cycle number for the test cell according to example 8.

Fig. 48 shows a graph of coulombic efficiency versus cycle number for the test cells according to example 8.

Fig. 49 shows a graph of the charge and discharge capacity of the test battery according to example 8.

Fig. 50 shows a graph of the charge and discharge energy of the test battery according to example 8.

Fig. 51 shows a graph of the variation of charging ToC (highest charge) voltage versus cycle number for the test battery according to example 8.

Fig. 52 shows a graph of the variation of the voltage from ToC (highest charge) to discharge versus the number of cycles for the test battery according to example 8.

Fig. 53 shows a graph of energy efficiency versus cycle number for the test cell according to example 9.

Fig. 54 shows a graph of coulombic efficiency versus cycle number for the test cells according to example 9.

Fig. 55 shows a graph of the charge and discharge capacity of the test battery according to example 9.

Fig. 56 is a graph showing charge and discharge energies of the test battery according to example 9.

Fig. 57 shows a graph of the variation of charging ToC (highest charge) voltage versus cycle number for the test battery according to example 9.

Fig. 58 shows a graph of the variation of voltage from ToC (highest charge) to discharge versus the number of cycles for the test battery according to example 9.

Fig. 59 shows a graph of energy efficiency versus cycle number for the test cell according to example 10.

Fig. 60 shows a graph of coulombic efficiency versus cycle number for the test cells according to example 10.

Fig. 61 shows a graph of the charge and discharge capacity of the test battery according to example 10.

Fig. 62 shows a graph of the charge and discharge energy of the test battery according to example 10.

Fig. 63 shows a graph of the variation of charging ToC (highest charge) voltage versus cycle number for the test battery according to example 10.

Fig. 64 shows a graph of the variation of voltage from ToC (highest charge) to discharge versus cycle number for the test cells according to example 10.

The drawings are provided by way of example and are not intended to limit the scope of the present invention.

Detailed Description

The present invention provides an electrolyte for use in a secondary, i.e., rechargeable, zinc halide energy storage battery (e.g., a bipolar fluid or non-fluid battery). In some embodiments, the electrolytes of the present invention are for use in a non-fluid battery.

I. Definition of

As used herein, the terms "electrochemical cell" or "battery" are used interchangeably to refer to a device capable of generating electrical energy through a chemical reaction or promoting a chemical reaction through the introduction of electrical energy.

As used herein, the term "battery" encompasses an electrical storage device comprising at least one electrochemical cell. A "secondary battery" is rechargeable, while a "primary battery" is non-rechargeable. For the secondary battery of the present invention, the battery anode is designated as the positive electrode during discharge and the negative electrode during charge.

As used herein, "electrolyte" refers to a substance that functions as an ionically conductive medium. For example, the electrolyte facilitates the transfer of electrons and cations in the battery. The electrolyte includes, for example, a metal halide salt (e.g., ZnBr)₂、ZnCl₂Etc.) of water solution.

As used herein, the term "electrode" refers to an electrical conductor for contacting a non-metallic portion of an electrical circuit (e.g., a semiconductor, an electrolyte, or a vacuum). The electrode may also be referred to as an anode or a cathode.

As used herein, the term "anode" refers to the negative electrode from which electrons flow during the discharge phase of the battery. The anode is also the electrode that undergoes chemical oxidation during the discharge phase. However, in a secondary or rechargeable battery, the anode is the electrode that undergoes chemical reduction during the charging phase of the battery. The anode is formed of an electrically conductive or semi-conductive material, such as a metal (e.g., titanium or TiC coated titanium), a metal oxide, a metal alloy, a metal composite, a semiconductor, or the like.

As used herein, the term "cathode" refers to the positive electrode into which electrons flow during the discharge phase of the battery. The cathode is also the electrode that undergoes chemical reduction during the discharge phase. However, in secondary or rechargeable batteries, the cathode is the electrode that undergoes chemical oxidation during the charging phase of the battery. The cathode is formed of a conductive or semiconductive material, e.g., a metal, metal oxide, metal alloy, metal composite, semiconductor, or the like.

As used herein, the term "bipolar electrode" refers to an electrode that functions as an anode of one cell and a cathode of another cell. For example, in a battery pack, a bipolar electrode serves as the anode in one cell and as the cathode in an immediately adjacent cell. In some examples, the bipolar electrode includes two surfaces: a cathode surface and an anode surface, wherein the two surfaces are connected by a conductive material. For example, a bipolar electrode plate may have opposing surfaces, one of which is an anode surface and the other of which is a cathode surface, and the conductive material has a thickness of the plate between the opposing surfaces.

As used herein, the term "halide" refers to a binary compound of a halogen and another element or root that is less electronegative (or more electropositive) than the halogen to produce a fluoride, chloride, bromide, iodide, or astatide compound.

As used herein, the term "halogen" refers to the elements fluorine, chlorine, bromine, iodine, and astatine occupying group VIIA (17) of the periodic table. Halogens are reactive non-metallic elements that form strongly acidic compounds with hydrogen, from which simple salts can be made.

As used herein, the term "anion" refers to any chemical entity having one or more permanent negative charges. Examples of anions include, but are not limited to, fluoride, chloride, bromide, iodide, arsenate, phosphate, arsenite, hydrogenphosphate, dihydrogenphosphate, sulfate, nitrate, hydrogensulfate, nitrite, thiosulfate, sulfite, perchlorate, iodate, chlorate, bromate, chlorite, hypochlorite, hypobromite, carbonate, chromate, hydrogencarbonate (bicarbonate), dichromate, acetate, formate, cyanide, amide, cyanate, peroxide, thiocyanate, oxalate, hydroxide, and permanganate.

As used herein, "glyme" refers to an ether (e.g., a glycol ether). Examples include, but are not limited to, monoglyme (i.e., 1, 2-glyme), diglyme (i.e., bis (2-methoxyethyl) ether), tetraglyme (i.e., tetraglyme), pentaglyme, hexaglyme, heptaglyme, or any combination thereof.

As used herein, "titanium material" may include, but is not limited to, titanium (in any oxidized state), TiC, alloys of TiC (e.g., TiC)_xM) (where x is 0, 1,2,3, or 4, and M is a metal), titanium carbohydride, titanium oxycarbide, titanium oxynitride, titanium oxycarbonitride, titanium suboxide, non-stoichiometric titanium-nitrogen compounds, and any combination thereof.

As used herein, "titanium carbide" is used interchangeably with "titanium carbide material" and includes, but is not limited to, TiC, alloys of TiC (e.g., TiC)_xM, where x is 0, 1,2,3, or 4, and M is a metal), titanium carbohydrides, non-stoichiometric titanium-nitrogen compounds, and combinations thereof.

As used herein, the term "zinc metal" refers to elemental zinc, also commonly referred to as Zn (0) or Zn⁰。

As used herein, the terms "dimethylether poly (ethylene glycol)", "DME-PEG", and "MPEG" are used interchangeably to refer to a polymer having the structure

Wherein n is an integer. DME-PEG1000 (or MPEG 1K) refers to a polymer having a number average molecular weight (M) of about 1000_n) DME-PEG polymer of (1), and DME-PEG2000 (or MPEG2K) means having a number average molecular weight (M) of about 2000_n) The DME-PEG polymer of (1).

As used herein, the term "dimethyl ether" refers to a compound having the formula CH₃OCH₃The organic compound of (1).

As used herein, the term "aggregate concentration" refers to the summed total concentration (e.g., wt%) of each component in a class of ingredients or a class of agents (e.g., quaternary ammonium agents). In one example, the aggregate concentration of one or more quaternary ammonium agents in the electrolyte is the summed total concentration (e.g., weight percent) of each of the constituent quaternary ammonium agents present in the electrolyte. Thus, if the electrolyte has three quaternary ammonium agents, the aggregate concentration of the three quaternary ammonium agents is the sum of the concentrations of each of the three quaternary ammonium agents present in the electrolyte. Also, if the electrolyte has only one quaternary ammonium agent, the aggregate concentration of the quaternary ammonium agent is simply the concentration of a single quaternary ammonium agent present in the electrolyte.

As used herein, the term "alcohol" refers to any organic compound whose molecule contains one or more hydroxyl groups attached to a carbon atom. Examples of alcohols include methanol, ethanol, 1-propanol (i.e., n-propanol), 2-propanol (i.e., isopropanol), 1-butanol (i.e., n-butanol), sec-butanol, isobutanol, tert-butanol, 1-pentanol, or any combination thereof.

As used herein, the term "hydroxyl group" refers to an — OH group.

As used herein, the term "glycol" refers to any of a class of organic compounds belonging to the alcohol family. In the molecule of the diol, two hydroxyl (-OH) groups are attached to different carbon atoms. Examples of diols include C_1-10A diol comprising ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, hexanediol, or any combination thereof. Other examples of diols include substituted ethylene glycols and substituted propylene glycols.

As used herein, the term "weight percent" and its abbreviation "wt%" are used interchangeably to refer to the product of the quotient of the mass of one or more components divided by the total mass of the mixture or product containing the components multiplied by 100 times.

When referring to the concentration of a component or ingredient of the electrolyte, as described herein, weight percent is based on the total weight of the electrolyte.

As used herein, the term "quaternary ammonium agent" refers toAny compound, salt, or material comprising a quaternary nitrogen atom. For example, quaternary ammonium agents include: ammonium halides (e.g. NH)₄Br、NH₄Cl or any combination thereof), tetraalkylammonium halides (e.g., tetramethylammonium bromide, tetramethylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, alkyl-substituted pyridinium halides, alkyl-substituted morpholine halides, combinations thereof, and the like), heterocyclic ammonium halides (e.g., alkyl-substituted pyrrolidinium halides (e.g., N-methyl-N-ethylpyrrolidinium halides or N-ethyl-N-methylpyrrolidinium halides), alkyl-substituted pyridinium halides, alkyl-substituted morpholine halides, viologens having at least one quaternary nitrogen atom, combinations thereof, and the like), or any combination thereof. The tetraalkylammonium halides can be substituted symmetrically or asymmetrically with respect to the substituent of the quaternary nitrogen atom.

As used herein, the term "viologen" refers to any bipyridinium salt derivative of 4-4' -bipyridine.

As used herein, the term "ammonium bromide complexing agent" refers to any compound, salt, or material that comprises a quaternary nitrogen atom, wherein the quaternary nitrogen atom is not part of an imidazolium, pyridinium, pyrrolidinium, morpholine, or phosphonium moiety. Examples of ammonium bromide complexing agents include: tetraethylammonium bromide, trimethylpropylammonium bromide, dodecyltrimethylammonium bromide, hexadecyltriethylammonium bromide, and hexyltrimethylammonium bromide.

As used herein, the term "imidazolium bromide complexing agent" refers to any compound, salt, or material that contains a quaternary nitrogen atom that is part of an imidazolium moiety. Examples of imidazolium bromide complexing agents include: 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-ethyl-2, 3-dimethylimidazolium bromide, 1-decyl-3-methylimidazolium bromide, 1-butyl-2, 3-dimethylimidazolium bromide, 1-methyl-3-octylimidazolium bromide, and 1-methyl-3-hexylimidazolium bromide.

As used herein, the term "pyridinium bromide complexing agent" refers to any compound, salt, or material that comprises a quaternary nitrogen atom that is part of a pyridinium moiety. Examples of pyridinium bromide complexing agents include: 1-ethyl-2-methylpyridinium bromide, 1-ethyl-3-methylpyridinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, 1-butyl-4-methylpyridinium bromide, and 1-hexylpyridinium bromide.

As used herein, the term "pyrrolidinium bromide complexing agent" refers to any compound, salt, or material that comprises a quaternary nitrogen atom that is part of a pyrrolidinium moiety. An example of a pyrrolidinium bromide complexing agent is 1-butyl-1-methylpyrrolidinium bromide.

As used herein, the term "morpholinium bromide complexing agent" refers to any compound, salt, or material that comprises a quaternary nitrogen atom, wherein the quaternary nitrogen atom is part of a morpholinium moiety. An example of a morpholinium bromide complexing agent is N-ethyl-N-methylmorpholinium bromide.

As used herein, the term "phosphonium bromide complexing agent" refers to any compound, salt, or material that comprises a quaternary phosphorus atom. An example of a phosphonium bromide complexing agent is tetraethylphosphonium bromide.

As used herein, the term "crown ether" refers to a cyclic compound consisting of a ring containing at least three ether groups. Examples of crown ethers include 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6, and diaza-18-crown-6.

As used herein, an "alkyl" group refers to a saturated aliphatic hydrocarbon group containing 1 to 20 (e.g., 1 to 16, 1 to 12, 1 to 8, 1 to 6, or 1 to 4) carbon atoms. The alkyl group may be linear or branched. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, dodecyl, and hexadecyl.

As used herein, used alone or as, for example, "aralkyl", "aryloxy" or "arylAn "aryl" group that is part of the larger moiety of an oxyalkyl "refers to a monocyclic (e.g., phenyl), bicyclic (e.g., indenyl, naphthyl, tetrahydronaphthyl, tetrahydroindenyl), tricyclic (e.g., fluorenyl, tetrahydrofluorenyl, anthracenyl, or tetrahydroanthracenyl), or benzofused group having 3 rings. For example, benzo-fused groups include groups with two or more C_4-8Phenyl fused in part to the carbocyclic ring structure. Aryl groups are optionally substituted with one or more substituents including: aliphatic (e.g., alkyl, alkenyl, or alkynyl), cycloalkyl, (cycloalkyl) alkyl, heterocycloalkyl, (heterocycloalkyl) alkyl, aryl, heteroaryl, alkapoxy, cycloalkoxy, heterocycloalkoxy, aryloxy, heteroaryloxy, aralkoxy, heteroaralkoxy, aroyl, heteroaroyl, amino, aminoalkyl, nitro, a carboxyl group, a carbonyl group (e.g., an alkoxycarbonyl group, an alkylcarbonyl group, a carbamoyl group, an (alkylamino) alkylaminocarbonyl group, an arylaminocarbonyl group, a heteroarylaminocarbonyl group, or a sulfonylcarbonyl group), an aralkylcarbonyloxy group, a sulfonyl group (e.g., an alkylsulfonyl group or an aminosulfonyl group), a sulfinyl group (e.g., an alkylsulfinyl group), a sulfonamido group (e.g., an alkylsulfonamido group), a cyano group, a halogen group, a hydroxyl group, an acyl group, a mercapto group, a sulfoxy group, urea, thiourea, a sulfonamide, a sulfamide, an oxy group, or a carbamoyl group. Alternatively, the aryl group may be unsubstituted.

Examples of substituted aryl groups include: haloaryl, alkoxycarbonylaryl, alkylaminoalkylaminocarbonylaryl, p, m-dihaloaryl, p-amino-p-alkoxycarbonylaryl, m-amino-m-cyanoaryl, aminoaryl, alkylcarbonylaminoaryl, cyanoalkylaryl, alkoxyaryl, aminosulfonylaryl, alkylsulfonylaryl, aminoaryl, p-halo-m-aminoaryl, cyanoaryl, hydroxyalkylaryl, alkoxyalkylaryl, hydroxyaryl, carboxyalkylaryl, dialkylaminoalkylaryl, m-heterocycloaliphatic-o-alkylaryl, heterocycloaminocarbonylaryl, nitroalkylaryl, alkylsulfonylaminoalkylaryl, heterocycloaliphatic carbonylaryl, alkylsulfonylalkylaryl, cyanoalkylaryl, and the like, Heterocyclic aliphatic carbonylaryl, alkylcarbonylaminoaryl, hydroxyalkylaryl, alkylcarbonylaryl, aminocarbonylaryl, alkylsulfonylaminoaryl, dialkylaminoaryl, alkylaryl, and trihaloalkylaryl groups.

As used herein, an "aralkyl" group refers to an alkyl group substituted with an aryl group (e.g., C)_1-4An alkyl group). Both "alkyl" and "aryl" are defined herein. An example of an aralkyl group is benzyl. A "heteroaralkyl" group refers to an alkyl group substituted with a heteroaryl group.

As used herein, a "cycloalkyl" group refers to a saturated carbocyclic, mono-, di-, or tri-or polycyclic (fused or bridged) having 3 to 10 (e.g., 5 to 10) carbon atoms. Without limitation, examples of monocyclic cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like. Examples of bicyclic cycloalkyl groups include, without limitation, octahydro-indenyl, decahydro-naphthyl, bicyclo [3.2.1] octyl, bicyclo [2.2.2] octyl, bicyclo [3.3.1] nonyl, bicyclo [3.3.2 ] decyl, bicyclo [2.2.2] octyl, bicyclo [2.2.1] heptanyl, bicyclo [3.1.1] heptanyl, and the like. Without limitation, polycyclic groups include adamantyl, cubyl (cubyl), norbornyl, and the like. The cycloalkyl ring may be optionally substituted at any chemically variable ring position.

As used herein, a "heterocycloalkyl" group refers to a 3-to 10-membered monocyclic or bicyclic (fused or bridged) (e.g., 5-to 10-membered monocyclic or bicyclic) saturated ring structure in which one or more of the ring atoms is a heteroatom (e.g., N, O, S or a combination thereof). Examples of heterocycloalkyl groups include optionally substituted piperidinyl, piperazinyl, tetrahydropyranyl, tetrahydrofuranyl, 1, 4-dioxolanyl, 1, 4-dithianyl, 1, 3-dioxolanyl, oxazolidinyl, isoxazolidinyl, morpholinyl, thiomorpholinyl, octahydro-benzofuranyl, octahydro-benzopyranyl, octahydro-thiochromanyl, octahydro-indolyl, octahydro-pyridinyl, decahydro-quinolinyl, octahydro-benzo [ b ] b]Thiophenyl, 2-oxa-bicyclo [2.2.2]Octyl, 1-aza-bicyclo [2.2.2]Octyl, 3-aza-bicyclo [3.2.1]Octyl, 2, 6-dioxa-tricyclo [3.3.1.0^3,7]Nonyl radical,Tropane. Monocyclic heterocycloalkyl groups may be fused to a phenyl moiety such as tetrahydroisoquinoline. The heterocycloalkyl ring structure may be optionally substituted at any chemically variable position on the ring or rings.

As used herein, a "heteroaryl" group refers to a monocyclic, bicyclic, or tricyclic ring structure having 4 to 15 ring atoms, wherein one or more of the ring atoms is a heteroatom (e.g., N, O, S or a combination thereof) and wherein one or more rings of the bicyclic or tricyclic ring structure is aromatic. Heteroaryl groups include benzo-fused ring systems having 2 to 3 rings. For example, benzo-fused groups include a group fused to one or two C_4-8Heterocyclic moieties (e.g. indolizinyl, indolyl, isoindolyl, 3H-indolyl, indolinyl, benzo [ b ]]Furyl, benzo [ b ]]Thiophenyl, quinolinyl, or isoquinolinyl) fused benzo. Some examples of heteroaryl groups are azetidinyl, pyridyl, 1H-indazolyl, furyl, pyrrolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, tetrazolyl, benzofuryl, isoquinolyl, benzothiazolyl, xanthene, thianthrene, phenothiazine, indoline, benzo [1,3 ] indole]Dioxoles, benzo [ b ]]Furyl, benzo [ b ]]Thiophenyl, indazolyl, benzimidazolyl, benzothiazolyl, purinyl (puryl), cinnolinyl, quinolyl, quinazolinyl, cinnolinyl, phthaloyl, quinazolinyl, quinoxalinyl, isoquinolyl, 4H-quinolizinyl (4H-quinolizyl), benzo-1, 2, 5-thiadiazolyl, or 1, 8-naphthyridinyl (1, 8-naphthyridinyl). Heteroaryl also includes bipyridine compounds.

Electrochemical cell and battery

Referring to fig. 1 to 23, in one aspect, the present invention provides a static (non-flow) bipolar zinc-halogen rechargeable electrochemical cell 100 and a battery pack 1000 of such cells.

A. Bipolar electrochemical cell

The bipolar electrochemical battery 100 of the present invention includes a bipolar electrode 102, a terminal assembly 104, and a zinc-halide electrolyte.

1. Bipolar electrode

The bipolar electrodes 102, 102' of the present invention comprise a bipolar electrode plate 208 having a front surface 212 and a rear surface 214, wherein the cathode assembly 202 is attached to the front surface of the bipolar electrode plate such that the cathode assembly is in electrical communication with at least the front surface of the bipolar electrode plate 208. The bipolar electrode 102 of the present invention is configured to plate zinc metal on an anode electrode surface (e.g., the back surface of an adjacent bipolar electrode or the inner surface of an end plate of a terminal anode assembly) and to generate inversely spaced halides or mixed halide species in the cathode assembly during charging of the electrochemical cell. Rather, the electrodes are configured to oxidize the plated zinc metal to produce Zn during discharge of the electrochemical cell²⁺Cations and reduces the halides or mixed halide species to their corresponding anions.

a. Bipolar electrode plate

The bipolar electrode plates 208, 208' of the present invention include a front surface 212 and a back surface 214. The cathode assembly is located on a front surface 212 (e.g., a cathode surface) of bipolar electrode plate 208. In some embodiments, the bipolar electrode plate comprises a conductive material that is inert with respect to the zinc halide electrolyte used in the electrochemical cell or battery. In some embodiments, the bipolar electrode plate 208 comprises a titanium material (e.g., titanium or titanium oxide). In some examples, the bipolar electrode plate 208 further comprises a coating or film covering at least a portion of the front surface 212, at least a portion of the back surface 214, or at least a portion of both surfaces. In other embodiments, the bipolar electrode plate comprises a titanium material coated with a titanium carbide material. Also, in some embodiments, the bipolar plate comprises a titanium material that is thermally diffused with carbon. In these embodiments, at least a portion of the front surface 212, at least a portion of the back surface 214, or at least a portion of both surfaces are coated with a titanium carbide material or thermally diffused with carbon. In some embodiments, the bipolar electrode plate comprises a conductive carbon material (e.g., graphite plate). In some examples, the bipolar electrode plate comprises a graphite plate coated with a titanium carbide material. In these embodiments, at least a portion of the front surface 212, the back surface 214, or at least a portion of any of these surfaces is coated with a titanium carbide material.

The bipolar electrode plate of the present invention optionally includes a recessed portion 215 on the front surface 212 of the bipolar electrode plate. In some embodiments, the bipolar electrode plate includes a recessed portion 215 on the front surface 212 of the bipolar electrode plate. In some of these embodiments, the peripheral edge of recessed portion 215 is generally defined by the outermost edge of flange 220 of cathode holder 216 of cathode assembly 202, such that the cathode assembly fits at least partially within recessed portion 215 when the bipolar electrode is assembled. In other embodiments, the peripheral edge of the recessed portion is at least partially within the outermost edge of flange 220 of cathode holder 216 of cathode assembly 202. In some of these embodiments, the recessed portion may be defined by the outermost edge of the carbon material 224 embedded within the cathode holder 216 of the cathode assembly 202 such that the carbon material 224 is at least partially installed within the recessed portion 215 of the bipolar electrode plate when the bipolar electrode 102 is assembled. Also, in some alternative embodiments, the front surface 212 of the bipolar electrode plate is free of recessed portions such that the surface is at least substantially flat.

The bipolar electrode plate of the present invention may optionally include one or more through-holes at or near the perimeter 204 of the plate. Referring to fig. 2A-4, in some embodiments, the bipolar electrode plate includes one or more through-

holes

206, 210 at or near the perimeter 204 of the plate, which may be used to fill the electrochemical cell with liquid electrolyte or may be used to align the electrolyte plate in the battery pack.

The bipolar electrolyte plate may be formed by stamping or other suitable process. A portion of the front surface 212, a portion of the back surface 214, or portions of both surfaces may optionally be subjected to a surface treatment (e.g., a coating, etc.) to enhance the electrochemical properties of the cell or battery. The rear surface of the bipolar electrode plate may include an electrochemically active area associated with or defined by the formation of a zinc metal layer when the cell or battery is charged. In some embodiments, the back surface of the electrode plate may be grit blasted (e.g., grit blasted with SiC or garnet), textured, or otherwise treated within the electrochemically active area. In other embodiments, the front surface may be grit blasted within the electrochemically active area associated with the area surrounded by the cathode assembly.

For example, in some embodiments, at least a portion of the back surface, at least a portion of the front surface, or at least portions of both surfaces are treated (e.g., grit blasted) to obtain a rough surface. In some examples, at least a portion of the rear surface of the bipolar electrode plate is treated (e.g., grit-blasted) to obtain a rough surface. In some examples, the area of the back surface treated to provide the roughened surface is generally defined by the perimeter of the cathode assembly attached to the front surface of the electrode plate.

b. Cathode assembly

The electrochemical cells and batteries of the present invention include at least one cathode assembly 202 formed from a cathode holder 216, a carbon material 224, and a separator 222.

i. Cathode holder

Cathode holder 216 includes pocket portion 218 and flange 220 and is disposed on the front surface 212, 212' of the bipolar electrode plate or on the inner surface 316 of the terminal end plate at flange 220. Referring to fig. 6A and 6B, a front view (fig. 6A) and a side view (fig. 6B) of the cathode holder 216 are shown. Cathode holder 216 comprises a length X₁And width Y₁The entire area defined, including the flange 220. To form the flanges, a flat metal sheet is mounted on a forming machine to stamp a flange on each of the four edges of the flat sheet. In some embodiments, the planar metal sheet comprises a titanium or titanium carbide material. In some embodiments, the cathode holder further comprises slits at the corners of the holder. These slits may be formed by laser cutting. Cathode holder 216 includes a length X corresponding to pocket portion 218₂And width Y₂A defined reduced area. Accordingly, X₁Greater than X₂And Y is₁Greater than Y₂. In the example shown, flange 220 is bent relatively flat with respect to pocket portion 218 to represent an X₁/X₂And Y₁/Y₂Size and depth of the pocket portion. In some embodiments, by X₂And Y₂The defined area represents an etched area in which a plurality of holes 227 are formed. Length X₁/X₂And width Y₁/Y₂May vary depending on the operational requirements of the electrochemical cell 100 or battery pack 1000.

In some embodiments, flange 220 includes a surface adjacent to and in contact with front surface 212 of the bipolar electrode plate, and the depth of pocket portion 218 extends from the flange in a direction away from the front surface of the electrode plate. The pocket portion 218 of the cathode holder functions in cooperation with the front surface of the electrode plate to form a chamber in which the separator 222 and carbon material 224 are located. In some of these embodiments, the cathode holder is disposed on the front surface of the electrode plate at its flange by welding, using an adhesive, using mechanical fasteners, or any combination thereof.

The cathode holder is formed of a metal, metal alloy, or plastic that is substantially inert with respect to the electrolyte of the electrochemical cell or battery. In some embodiments, the cathode holder is stamped from a titanium material (e.g., titanium or titanium oxide). In other embodiments, the cathode holder comprises a titanium material coated with a titanium carbide material.

In some embodiments, the pocket portion of the cathode holder is chemically etched to form a plurality of spaced apart holes 227. In some embodiments, the size and spacing of the apertures is designed to form an aperture pattern (e.g., a tuned aperture pattern) that increases the uniformity of current and/or charge distributed on the cathode holder by compensating for deformation or bending of the pocket portion of the cathode holder that occurs during operation (e.g., charging or discharging) of the electrochemical cell.

Fig. 7A shows a front view of cathode holder 216 from fig. 6A, including a plurality of apertures 227 formed by chemical etching through the chemically etched surface of pocket portion 218. Fig. 7B is a detailed view of a portion shown in fig. 7A, showing the distribution of the plurality of apertures 227. The chemical etching process is a subtractive manufacturing process that eliminates solid material to be removed for forming the plurality of holes 227. During the first step of the chemical etching process, the cathode holder 216 starts out as a flat metalA sheet of metal cut with a guillotine to obtain a cut corresponding to X₁And Y₁The size of (c). Next, the metal sheet can be cleaned and dry film coated in a hot roll laminator for solder resistance, followed by cooling in dark environment. A protective film may then be applied within the vacuum exposure unit to expose the metal sheet. In some instances, the amount of exposure may be measured with a step indicator, and the exposure determined when the desired exposure is obtained. Subsequently, the metal sheet is passed through a developer to remove the protective film, while a decomposing detergent in the developer is applied to the metal sheet to remove excess unexposed resist. The metal sheet may then be placed on a heating hob and baked at a predetermined temperature for a predetermined period of time. For example, the baking temperature may be about 250 ° F for about 60 minutes. After the bake cycle, each metal piece is air cooled and targeted to the desired etch area (e.g., by X)₂And Y₂Defined area) is programmed to run the baked and cooled metal sheet through the metal etching apparatus to remove excess material and thereby form the hole 227.

Referring now to fig. 7B, a plurality of apertures 227 are spaced along the rows and distributed in a pattern. In some embodiments, the pattern is an alternating repeating pattern. In some embodiments, the pattern is selected to achieve an even distribution of current over the cathode holder 216 in the presence of the cathode holder bending and deforming from flat during charging of the electrochemical cell or battery. Referring also to fig. 30A through 31C, providing a cathode holder with a hole pattern according to the present invention enhances the uniform distribution of charge and/or current that produces a more uniform plating of zinc metal at the anode surface of the bipolar electrode plate (e.g., the rear surface 214 of the bipolar electrode plate, or the inner surface 318 of the end plate, or both surfaces) during a charging cycle. Likewise, the conversion between bromine and bromide ions at or near the cathode holder 216 may also be enhanced. In some embodiments, the spacing between each of the plurality of holes 227 along each row in the x-direction, the spacing between alternating rows in the y-direction, and the diameter of the holes

May be selected to achieve a generally uniform distribution of charge and/or current on the cathode holder 216 based on the amount of deflection or deformation of the cathode holder and bipolar electrodes caused when the electrochemical cell or battery undergoes charging and discharging. In some embodiments, the distribution (e.g., spacing) of x and y aperture locations in each of the x and y directions is based on the nominal aperture area and the recommended grid length of cathode holder 216. The thickness of the surface of pocket portion 218 may determine the dimensions of the nominal aperture area and the recommended mesh length. In some examples, centers of adjacent plurality of apertures 227 along a row are spaced apart by about 0.067cm in the x-direction and each other row is spaced apart by about 0.152cm in the y-direction. As described in more detail below, the cathode holder 216 and bipolar electrode plates 208, 208' or terminal end plate 302 are bent from flat a greater distance at each component in an area that is farther from the perimeter, resulting in a shorter spacing between the cathode and anode electrodes relative to the outer area near the perimeter where the central area is removed. Generally, as the spacing between the anode electrode and the cathode electrode decreases, the calculated hole diameters at the corresponding x and y hole locations will increase.

In some embodiments, the spacing between the counter electrodes (e.g., between the cathode holder 216 and the rear surface 214 or inner surface 318 of the bipolar electrode plate 208, 208', 302) is in an etched region (e.g., by X) along the cathode holder₂And Y₂Defined area) is calculated at each of a plurality of evenly distributed x and y aperture locations. The x-y origin may include the lower left boundary where the x-axis and y-axis intersect in pocket portion 218 shown in FIG. 7B. The aperture area for each of the plurality of apertures 227 may then be calculated based on the calculated spacing between the cathode and anode electrodes at each x and y position, the predetermined minimum spacing between the electrodes, and the nominal aperture area. In some embodiments, the number of plurality of apertures 227 may be further based on the thickness of the surface of pocket portion 218 of cathode holder 216. In some examples, the predetermined minimum spacing is about 7.45mm and the nominal aperture area is about 1.08mm². In some embodiments, a plurality of etching regions are formed along the etching regionCalculating the spacing between the anode electrode and the cathode electrode at each of the x and y positions using the following fit equation is calculated using the following fit equation:

f＝y0+a*x+b*y+c*x²+d*y² [1]。

the coefficients of the fitting equation of equation [1] may be determined by measuring the amount of change Δ from flatness for each cathode holder 216 and the electrode plate 208' or terminal end plate 302 of each bipolar electrode. Measurements are obtained from a plurality of x and y hole locations on each cathode holder 216 and corresponding locations at the electrode plate 208'. An average is calculated at each location for each of the plurality of bipolar electrodes 102, for both the cathode holder 216 and the electrode plate 208' or the terminal end plate 302. Data corresponding to the calculated average values are used to determine the coefficients y0, a, b, c, and d for each of the cathode holder and the electrode plate. In some embodiments, the direction of the change Δ for each of the two electrodes is adjusted such that the flat distance between the two is a desired pitch, e.g., about 10.0mmm, and the change Δ for the electrode plate extends upward from about 0mm and the change Δ for the cathode holder extends downward from about 10.0 mm. Accordingly, the coefficients determined for each of the electrode plates and the cathode holder are as follows:

electrode plate/terminal end plate

y0＝-1.5787

a＝0.8948

b＝2.4920

c＝-0.1268

d＝-0.9132

e＝0.0000

Cathode holder

y0＝10.8602

a＝-0.5295

b＝-1.5860

c＝0.0814

d＝0.6857

e＝0.0000

The new coefficients of the fitting equation of input equation [1] can be determined by subtracting the anode coefficients from the cathode coefficients. Accordingly, the new coefficients for input equation [1] are as follows:

y0＝12.4389

a＝-1.4243

b＝-4.078

c＝0.2082

d＝1.5989

e＝0.0000

after being input into equation [1]]Previously, the x and y hole locations had to be normalized by the etched area for calculating the spacing of the plurality of holes 227. For example, each X position is divided by length X of pocket portion 218₂And each Y position divided by the width Y of the pocket portion₂. Each normalized x and y hole location is then input into equation [1] along with the new coefficients determined above]To determine the spacing between the anode and cathode electrodes at each x and y aperture location. Equation [1]]The fitting equation of (a) is a nonlinear three-dimensional parabolic equation. In some embodiments, equation [1]]Sigmaplot with Systal software company license^TMSoftware is executed.

In some embodiments, the area of each of the plurality of apertures 227 at each x and y position may be calculated as follows:

wherein

Is the calculated diameter at each hole location,

f is the spacing between the electrodes at each hole location calculated using equation 1,

A_nominalis a nominal pore area, and

S_{nominal_minimum}is the nominal minimum hole spacing.

In some examples, the nominal aperture area is about 1.08mm²And a nominal minimum separation of 7.45mm². An example for calculating the hole diameter utilizes a mixing unit where the hole positions are for X and y and from X₂And Y₂Each of the defined etching areas utilizes quartzInches, and millimeters are used for calculating the spacing between the electrodes. Equation [ 2]]It is demonstrated that the pore diameter increases with increasing spacing between the anode and cathode electrodes. The average pore diameters calculated at each pore location using equation 2 for each of the bipolar electrodes 102, 102' are averaged. Embodiments include utilizing the average pore diameter for the plurality of pores 227 formed in the cathode holder 216 for each of the plurality of bipolar electrodes 102, 102'.

Fig. 10 and 11 show experimental data of the average spacing between the three dimensional profiles of the bipolar electrode plate 208' and cathode holder 216 relative to the x-axis (fig. 10) and y-axis (fig. 11). The experimental data show the average values obtained from the twenty bipolar electrodes 102, 102' of the battery module 1000. The electrode plate 208' and cathode holder 216 are bent from flat when charged. In the example shown, the cathode holder and the electrode plate are arranged such that the distance between the cathode holder and the electrode plate is flat at a spacing of about 10mm with respect to the z-axis. The electrode plate has a maximum delta of about 1.566mm along the z-axis distance flat at the immediate center (e.g., about 3.5mm relative to the x-axis), and the cathode holder has a maximum delta of about 0.565mm along the x-axis distance flat at the right center (e.g., about 2.0mm relative to the x-axis). The average inter-electrode spacing from the left center to the right center of the plurality of bipolar electrodes was about 7.78 mm.

Carbon Material

The carbon material 224 is in electrical communication with the front surfaces 212, 212 'of the bipolar electrodes 208, 208' and is bounded by the cathode holders 216, 216', the separator 222, and the front surfaces 212, 212' of the bipolar electrodes. Carbon materials suitable for the electrochemical cells of the present invention may comprise any carbon material that is capable of reversibly absorbing aqueous bromine species (e.g., aqueous bromine or aqueous bromide) (collectively 702) and is substantially chemically inert in the presence of an electrolyte. In some embodiments, the carbon material comprises carbon black or other furnace process carbon. Suitable carbon black materials include, but are not limited to, Cabot

XC72R, Akzo-Nobel Ketjenblack EC600JD, and other mills for conductive furnace process carbon blackAnd (4) mixing sand and black. In some embodiments, the carbon material may also include other components including, but not limited to, PTFE binder, carbon fibers, and deionized water. For example, the carbon material has a water content of less than 50 wt% (e.g., about 0.01 wt% to about 30 wt%) by weight of the carbon material. In some examples, the carbon material comprises PTFE (e.g., from about 0.5 wt% to about 5 wt% by weight of the carbon material).

In some embodiments, the carbon material is molded into a size and shape such that the carbon material is at least partially nestable by the cathode holder. In some examples, the carbon material may be in the form of one or more thin rectangular blocks. For example, the carbon material is shaped into one or more thin rectangular blocks with rounded corners so that the corners do not penetrate the separator plate when the cathode assembly is assembled. In some embodiments, the carbon material may comprise a single solid block. In other embodiments, the carbon material may comprise one to five, one to three, or one to two carbon blacks.

iii. a separator plate

The separator 222 that may be used in the electrochemical cell or battery of the present invention is capable of forming a porous barrier between the reduced surface of at least the pocket portion of the cathode holder and the carbon material. In some embodiments, the spacer is formed of a conductive material that enables electron transport. In some embodiments, the separator is formed of a wettable woven or wettable non-woven fabric, either of which is electrically conductive. In other embodiments, the separator is formed of a wettable woven or wettable non-woven fabric. Also, in some examples, the woven or non-woven cloth includes a plurality of pores sized to allow passage of electrolyte therethrough while at least substantially restricting passage of carbon material particles therethrough. In other embodiments, the separator is formed from a carbon cloth comprising carbon fibers

FM10 ACC 100% activated woven carbon cloth with very large surface area (e.g., 1000-2000 m)²/g) and/or exhibit rapid reaction and adsorption kinetics. In some embodiments, the separator is made of graphiteAnd (4) forming the cloth.

In some embodiments, separator 222 is interposed between at least a portion of the cathode holder and the carbon material. And, in other embodiments, the separator substantially encapsulates the carbon material such that the separator is between the carbon material and substantially all of the pocket portion of the cathode holder, and the separator is between at least a portion of the carbon material and at least a portion of the bipolar electrode plate. For example, a separator is interposed between at least the reduced surface of the cathode holder having a pattern of holes (e.g., plurality of holes 227) and the carbon material.

2. Terminal assembly

Another aspect of the invention provides a terminal assembly for a bipolar electrochemical cell or battery. Referring to fig. 12-17, the terminal assembly 104 of the present invention includes an electrically conductive cup-shaped member 310, the cup-shaped member 310 including a terminal wall 312, a sidewall 304, and a rim 306 spaced from the terminal wall by the sidewall. The terminal 308 of the bipolar electrochemical cell or battery is connected for electrical communication with the terminal wall 312 of the conductive cup-shaped member 310. In some embodiments, the terminal 308 comprises brass (e.g., the terminal is a brass plug in electrical communication with or in contact with a terminal wall). In some embodiments, the portion of the terminal wall 312 that contacts the terminal 308 comprises copper. In these embodiments, the terminal walls may be formed of titanium and include copper plates operable for contacting and electrically connecting terminals formed of copper to the terminal walls of the conductive tape cup member.

The terminal assembly further includes a terminal endplate 302, the terminal endplate 302 having an inner surface 318 and an outer surface 316 at least substantially coplanar with the terminal walls and joined to the edge at the outer surface 316. The terminal end plate 302 may be shaped to include any of the features present in the bipolar electrode plate, including, but not limited to, a titanium material coated with a titanium carbide material, through holes, a roughened inner surface, and the like. The rim of the cup-shaped member is joined to the terminal end plate 302 such that the rim is approximately in the center of the electrochemically active area 322 of the terminal end plate. In some embodiments, the electrochemically active area 322 corresponds to an area extending between the inner and outer surfaces of the terminal end plate that is in chemical or electrical communication with an adjacent bipolar electrode during charge and discharge cycles of the electrochemical cell or battery. In these embodiments, the electrochemically active area of the terminal end plate associated with the negative cathode terminal of the battery corresponds to, or is defined by, the area encompassed by the cathode assembly disposed on the inner surface of the terminal end plate (e.g., the terminal cathode end plate). The electrochemically active area of the terminal end plate associated with the positive anode terminal of the battery may correspond to an area on the inner surface thereof that opposes the cathode assembly disposed on the front surface of the adjacent bipolar electrode plate and forms a zinc metal layer when the battery (terminal anode assembly) is charged. In some embodiments, at least a portion of the inner surface (e.g., at least the chemically active area) of the terminal end plate of the terminal anode assembly is a roughened surface.

Fig. 14 provides a top view of the terminal end plate showing the electrochemically active area of the terminal end plate including a first surface area 326 enclosed within the dashed oval 306 corresponding to the outer perimeter of the rim and a remaining second surface area 324 defined by the outer perimeter of the rim 306 and the peripheral edge of the electrochemically active area 322. For clarity, the conductive cup-shaped member 310 is removed in fig. 14 so that the first surface area can be shown. Whereby the first surface area is surrounded by the rim when the electrically conductive cup-shaped member is joined to the outer surface of the terminal end plate. The first 326 and second 324 surface areas are substantially equal.

In some embodiments, the edge is generally elliptical and defined by a major axis A_MAJAnd a minor axis A perpendicular to the major axis_MINIt is defined that the major and minor axes intersect at the center of the edge and also at the center of the electrochemically active area. As used herein, a substantially elliptical edge refers to an edge having a substantially rectangular shape with rounded or otherwise curved and rounded corners. In some embodiments, the edges are substantially rectangular. FIG. 15 provides a cross-sectional view taken along line 15-15 of FIG. 13 showing the major radius R of the edge_MAJSubstantially equal to a first distance D1, said first distance D1 extending from the outer periphery of the edge along the major axis to the peripheral edge of the electrochemically active area parallel to the minor axis, and13 shows the short radius R of the edge_MINSubstantially equal to a second distance D2, the second distance D2 extending from the outer perimeter of the rim along the minor axis to the perimeter edge of the electrochemically active area parallel to the major axis,

in some embodiments, the rim defines an opening to an interior region 330, the interior region 330 is defined by interior surfaces defined by the terminal walls and the side walls, and an exterior surface of the terminal end plate surrounds the opening to the interior region when joined to the rim.

In some embodiments, the rim is centered within the electrochemically active area of the end plate. In some embodiments, the edge is substantially circular or substantially elliptical.

In some embodiments, the sidewalls are perpendicular or substantially perpendicular to the terminal walls and edges. In other embodiments, the side wall extends radially outward from the terminal wall to the edge.

In some embodiments, the edge is substantially circular. For example, fig. 16 provides a top perspective view of a terminal assembly including an electrically conductive cup-shaped member including a terminal wall, a side wall, and a generally circular rim 306' spaced from the terminal wall by the side wall. In these embodiments, the radius R1 of the edge is substantially equal to the distance D3 between the peripheral edge of the electrochemically active area 322 and the outer periphery of the edge.

Referring to fig. 17, a cross-sectional view taken along line 17-17 of fig. 13 shows that the terminal assembly includes an electrically conductive cup-shaped member, a terminal end plate, an optional frame member 114, and a bipolar electrode proximate the terminal assembly, wherein the bipolar electrode includes a cathode assembly 202 and a bipolar electrode plate 208. Referring to fig. 17 and 23, in some embodiments, frame member 114 includes a first side 614 and a second side 616 that oppose and receive inner surface 318 of terminal endplate 302 on a side opposite conductive cup member 312. In some of these embodiments, the second side of the frame member opposes the cathode assembly 202 of the bipolar electrode, and the bipolar electrode comprises a bipolar electrode plate 208, the bipolar electrode plate 208 comprising a front surface 212 secured to the second side 616 of the frame member, and a cathode assembly 202 on the front surface of the bipolar electrode plate, the cathode assembly being interposed between the front surface of the bipolar electrode plate and the inner surface of the terminal end plate. In some embodiments, the electrochemically active area 322 at the inner surface of the terminal end plate opposes the cathode assembly on the front surface of the bipolar electrode plate and comprises a size and shape that is substantially the same as the size and shape of the cathode assembly. As discussed in more detail above with reference to fig. 3 and 4B, the cathode assembly 202 includes a cathode holder 216, a separator 222, and a carbon material 224 on the front surface 212, 212' of the bipolar electrode plate.

In some embodiments, the terminal assembly is a terminal cathode assembly, wherein the terminal cathode assembly includes a terminal endplate 302 having an electrochemically active area, an electrically conductive cup-shaped member (any of which are described herein) disposed on an exterior surface of the terminal endplate and approximately centered in the electrochemically active area, and a cathode assembly (any of which are described herein) disposed on an interior surface of the terminal endplate.

In some embodiments, the terminal assembly comprises a terminal anode assembly, wherein the terminal anode assembly comprises a terminal end plate having an electrochemically active area, an electrically conductive cup-shaped member (any of the cup-shaped members described herein) disposed on an outer surface of the terminal end plate and approximately centered in the electrochemically active area, and wherein the terminal anode assembly is free of a cathode assembly.

In some embodiments, the edge of the conductive cup-shaped member is joined to the outer surface of the terminal end plate by welding or adhesive. In some examples, the adhesive is electrically conductive. Examples of suitable conductive adhesives include graphite-filled adhesives (e.g., graphite-filled epoxy, graphite-filled silicone, graphite-filled elastomer, or any combination thereof), nickel-filled adhesives (e.g., nickel-filled epoxy), silver-filled adhesives (e.g., silver-filled epoxy), copper-filled adhesives (e.g., copper-filled epoxy), any combination thereof, and so forth.

In some embodiments, the conductive cup-shaped member is comprised of at least one of a copper alloy, a copper/titanium cladding, aluminum, and a conductive ceramic. For example, the interior surfaces of the terminal walls and sidewalls comprise copper. In other examples, the exterior surfaces of the terminal walls and the sidewalls include at least one of copper, titanium, and a conductive ceramic.

In some embodiments, at least one of the conductive cup-shaped member or the terminal end plate comprises titanium. In some embodiments, at least one of the conductive cup-shaped member or the terminal end plate comprises a titanium material coated with a titanium carbide material.

In some embodiments, the electrically conductive cup-shaped member comprises a first metal and the end plate comprises a second metal.

In some embodiments, the rim includes a flange 328 (fig. 15) extending radially outward from the sidewall.

Referring again to fig. 15, the electrical characteristics of an exemplary terminal assembly for a zinc-halogen electrochemical cell or battery pack during its operation (e.g., charging or discharging) are summarized according to the following expression:

V_A≈V_E≈V_Cexpression 1

V_D≈V_BExpression 2

V_F≈V_GExpression 3

ΔV_G-D≈ΔV_F-B>>ΔV_H-G≈ΔV_F-H Expression 4

ΔV_G-D≈ΔV_F-B>>ΔV_B-C≈ΔV_D-C Expression 5

B and D identify two electrical contact points between the rim of the cup-shaped member and the first surface of the bipolar endplate. H represents the antisymmetric center of the conductive cup-shaped member, and C represents the overlap of H on the first surface of the bipolar endplate such that along the minor axis A_MINA line CH extending and connecting C and H is orthogonal to the first surface of the end plate. F and G identify the intersection where the terminal wall 312 and the side wall 304 meet, while a and E identify the opposing peripheral edges of the electrochemically active area 322.

Electric charge V at A_AAbout equal to the charge V at E_EAnd charge at CV_C. Charge V at D_DAbout equal to charge V at B_B. Charge V at F_FEqual to the charge V at G_G. Potential difference or voltage Δ V from G to D_G-DApproximately equal to voltage Δ V from F to B_F-BVoltage Δ V from H to G_H-GApproximately equal to voltage Δ V from F to H_F-HAnd Δ V_G-DAnd Δ V_F-BSubstantially greater than Δ V_H-GAnd Δ V_F-H. And, the voltage Δ V_G-DAnd Δ V_F-BSubstantially greater than the voltage Δ V from B to C_B-CAnd a voltage Δ V from D to C_D-C。

Due to the voltage from G to D and the voltage from F to B (i.e., Δ V)_G-DAnd Δ V_F-B) Substantially greater than the voltage from H to G and the voltage from F to H (i.e., Δ V)_H-GAnd Δ V_F-H) The current discharged from the terminals of the terminal assembly of the present invention is substantially more uniform than the discharge current from a conventional bipolar battery having terminals directly attached to the end plates.

3. Zinc-halogen electrolyte

In the electrochemical cells and batteries of the invention, the aqueous electrolyte (i.e., zinc-halide electrolyte) is interposed between the inner surfaces of the terminal end plates, the cathode assembly, the front surfaces of the bipolar electrodes, and the interior surfaces of the frame, if present. In these embodiments, upon charging of the electrochemical cell or battery, bromide anions exposed to the electrolyte at the surface of the cathode holder of the cathode assembly are oxidized to bromine. Instead, during discharge, bromine is reduced to bromide anions. The conversion 232 between bromine and bromide anions at or near the cathode holder of the cathode assembly can be expressed as follows:

Br₂+2e^-→2Br^-。

the present invention provides an aqueous electrolyte that can be used in a flow or non-flow (i.e., static) rechargeable zinc halide electrochemical cell or battery. In these cells or batteries, zinc bromide, zinc chloride, or any combination of the two, is present in the electrolyte and is used as the electrochemically active material.

One aspect of the present invention providesAn electrolyte for use in a secondary zinc-bromine electrochemical cell (e.g., a static cell) is provided that includes about 30 wt.% to about 40 wt.% ZnCl₂Or ZnBr₂About 5 wt% to about 15 wt% KBr, about 5 wt% to about 15 wt% KCl, and one or more quaternary ammonium agents, wherein the electrolyte comprises about 0.5 wt% to about 10 wt% of the one or more quaternary ammonium agents.

In some embodiments, the electrolyte comprises about 4 wt% to about 12 wt% (e.g., about 6 wt% to about 10 wt%) potassium bromide (KBr). In some embodiments, the electrolyte comprises about 8 wt% to about 12 wt% potassium bromide (KBr).

In some embodiments, the electrolyte comprises from about 4 wt% to about 12 wt% (e.g., from about 6 wt% to about 10 wt%) potassium chloride (KCl). In some embodiments, the electrolyte comprises from about 8 wt% to about 14 wt% potassium chloride (KCl). In some embodiments, the electrolyte comprises from about 11 wt% to about 14 wt% potassium chloride (KCl).

In some embodiments, the electrolyte further comprises about 0.5 wt.% to about 10 wt.% (e.g., about 1 wt.% to about 7.5 wt.%) of glyme. In some embodiments, the glyme comprises monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or any combination thereof. For example, glyme includes tetraglyme. In other examples, the electrolyte comprises about 1 wt% to about 5 wt% tetraglyme.

In some embodiments, the electrolyte further comprises about 0.05 wt% to about 4 wt% (e.g., about 0.1 wt% to about 1 wt%) of an ether. In some embodiments, the ether is a crown ether, DME-PEG, dimethyl ether, or any combination thereof. In another embodiment, the ether is a crown ether.

In some embodiments, the electrolyte further comprises from about 0.5 wt% to about 2.5 wt% (e.g., from about 1 wt% to about 2.25 wt%) of DME-PEG or dimethyl ether. In some examples, the DME-PEG has an average molecular weight of about 350amu to about 3000amu (e.g.Number average molecular weight M_n). In other examples, the DME-PEG has an average molecular weight of about 1200amu to about 3000 amu. And, in other examples, the electrolyte further comprises from about 5 wt% to about 10 wt% of DME-PEG, wherein the DME-PEG has an average molecular weight (e.g., number average molecular weight M) of from about 1500amu to about 2500amu (e.g., about 2000amu)_n)。

In some embodiments, the ether is a crown ether. For example, the crown ether is 18-crown-6. For example, the crown ether is 15-crown-5. For example, the crown ether is 12-crown-4.

In some embodiments, the electrolyte further comprises about 0.1 wt% to about 1.0 wt% of an alcohol, wherein the alcohol is substantially miscible in water. For example, the alcohol includes C_1-4An alcohol. In other examples, the alcohol comprises methanol, ethanol, 1-propanol (i.e., n-propanol), 2-propanol (i.e., isopropanol), 1-butanol (i.e., n-butanol), sec-butanol, isobutanol, tert-butanol, 1-pentanol, or any combination thereof. And in some examples, the electrolyte further comprises from about 0.25 wt% to about 0.75 wt% of tertiary butanol.

In some embodiments, the electrolyte further comprises about 0.25 wt% to about 5 wt% (e.g., about 0.5 wt% to about 4 wt%) C_1-10A diol. In some examples, the electrolyte further comprises about 0.25 wt.% to about 5 wt.% (e.g., about 0.5 wt.% to about 4 wt.%) substituted ethylene glycol or substituted propylene glycol. In some examples, the diol comprises ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, hexanediol, or any combination thereof. And, in some examples, the electrolyte further comprises from about 0.25 wt% to about 2.5 wt% neopentyl glycol.

One aspect of the invention provides an electrolyte for use in a secondary static zinc-bromine electrochemical cell (e.g., a static cell) comprising about 30 wt.% to about 50 wt.% (e.g., about 35 wt.% to about 47.5 wt.% or about 37 wt.% to about 46 wt.%) ZnBr₂About 22.5 wt.% to about 40 wt.% (e.g., about 23.75 wt.% to about 38 wt.% or about 24 wt.% to about 36 wt.%) of H₂O, about 3.00 wt% toAbout 9.5 wt% (e.g., about 4.00 wt% to about 8.5 wt%, about 3.00 wt% to about 8.5 wt%, or about 4.1 wt% to about 8 wt%) KBr, about 7.75 wt% to about 14.0 wt% (e.g., about 7.9 wt% to about 13.25 wt% or about 8 wt% to about 13 wt%) KCl, about 0.25 wt% to about 2.25 wt% (e.g., about 0.35 wt% to about 2.0 wt% or about 0.5 wt% to about 2 wt%) MPEG2K, about 0.075 wt% to about 1.25 wt% (e.g., about 0.1 wt% to about 1 wt%) MPEG 1K, about 0.35 wt% to about 2.75 wt% (e.g., about 0.4 wt% to about 2.65 wt%, or about 0.5 wt% to about 2.5 wt%) neopentyl glycol.

In some embodiments, the one or more quaternary ammonium agents comprise a quaternary ammonium compound having formula N⁺(R^A)(R^B)₃X^-In which R is^AIs C_1-6Alkyl (e.g., methyl, ethyl, propyl, butyl, etc.), R^BIs C_1-6Alkyl (e.g., methyl, ethyl, propyl, butyl, etc.), and X^-Is Br^-Or Cl^-. In some embodiments, the one or more quaternary ammonium agents are at least one selected from triethylmethylammonium chloride, tetraethylammonium bromide, and/or trimethylpropylammonium bromide. In some embodiments, the electrolyte comprises up to 5 (e.g., 1,2,3,4, or 5) different quaternary ammonium agents. For example, the electrolyte comprises triethylmethylammonium chloride. In other examples, the electrolyte comprises triethylmethylammonium chloride and tetraethylammonium bromide. Also, in some examples, the electrolyte comprises triethylmethylammonium chloride, tetraethylammonium bromide, and trimethylpropylammonium bromide.

In one example, the electrolyte comprises about 30 wt% to about 50 wt% (e.g., about 35 wt% to about 47.5 wt% or about 37 wt% to about 46 wt%) ZnBr₂About 22.5 wt.% to about 40 wt.% (e.g., about 23.75 wt.% to about 38 wt.% or about 24 wt.% to about 36 wt.%) of H₂O, about 3.00 wt% to about 9.5 wt% (e.g., about 4.00 wt% to about 8.5 wt%, about 3.00 wt% to about 8.5 wt%, or about 4.1 wt% to about 8 wt%)%) KBr, about 7.75 wt% to about 14.0 wt% (e.g., about 7.9 wt% to about 13.25 wt% or about 8 wt% to about 13 wt%), about 0.25 wt% to about 2.25 wt% (e.g., about 0.35 wt% to about 2.0 wt% or about 0.5 wt% to about 2 wt%) MPEG2K, about 0.075 wt% to about 1.25 wt% (e.g., about 0.1 wt% to about 1 wt%) MPEG 1K, about 0.35 wt% to about 2.75 wt% (e.g., about 0.4 wt% to about 2.65 wt% or about 0.5 wt% to about 2.5 wt%) neopentyl glycol, about 3.5 wt% to about 15 wt% (e.g., about 4 wt% to about 13 wt%) of a first quaternary ammonium agent (e.g., triethylmethylammonium chloride), and about 0.35 wt% to about 3.75 wt% of a second quaternary ammonium agent (e.g., tetraethylammonium bromide).

In another example, the electrolyte comprises about 30 wt% to about 50 wt% (e.g., about 35 wt% to about 47.5 wt% or about 37 wt% to about 46 wt%) ZnBr₂About 22.5 wt.% to about 40 wt.% (e.g., about 23.75 wt.% to about 38 wt.% or about 24 wt.% to about 36 wt.%) of H₂O, about 3.00 wt% to about 9.5 wt% (e.g., about 4.00 wt% to about 8.5 wt%, about 3.00 wt% to about 8.5 wt%, or about 4.1 wt% to about 8 wt%) KBr, about 7.75 wt% to about 14.0 wt% (e.g., about 7.9 wt% to about 13.25 wt% or about 8 wt% to about 13 wt%) KCl, about 0.25 wt% to about 2.25 wt% (e.g., about 0.35 wt% to about 2.0 wt% or about 0.5 wt% to about 2 wt%) MPEG2K, about 0.075 wt% to about 1.25 wt% (e.g., about 0.1 wt% to about 1 wt%) MPEG 1K, about 0.35 wt% to about 2.75 wt% (e.g., about 0.4 wt% to about 2.65 wt% or about 0.5 wt% to about 2.5 wt%) neopentyl glycol, about 3.5 wt% to about 15 wt% (e.g., a first agent), triethylmethylammonium chloride), from about 0.35 wt% to about 3.75 wt% of a second quaternary ammonium agent (e.g., tetraethylammonium bromide), and from about 0.35 wt% to about 2.75 wt% (e.g., from about 0.5 wt% to about 2.5 wt%) of neopentyl glycol.

And, in anotherIn one example, the electrolyte comprises about 30 wt% to about 50 wt% (e.g., about 35 wt% to about 47.5 wt% or about 37 wt% to about 46 wt%) ZnBr₂About 22.5 wt.% to about 40 wt.% (e.g., about 23.75 wt.% to about 38 wt.% or about 24 wt.% to about 36 wt.%) of H₂O, about 3.75 wt% to about 9.5 wt% (e.g., about 4 wt% to about 8.5 wt% or about 4.1 wt% to about 8 wt%) KBr, about 7.75 wt% to about 13.5 wt% (e.g., about 7.9 wt% to about 13.25 wt% or about 8 wt% to about 13 wt%) KCl, about 0.25 wt% to about 2.25 wt% (e.g., about 0.35 wt% to about 2.0 wt% or about 0.5 wt% to about 2 wt%) MPEG2K, about 0.075 wt% to about 1.25 wt% (e.g., about 0.1 wt% to about 1 wt%) MPEG 1K, about 0.35 wt% to about 2.75 wt% (e.g., about 0.4 wt% to about 2.65 wt% neopentyl glycol or about 0.5 wt% to about 2.5 wt% quaternary ammonium chloride, about 3.5 wt% to about 15.65 wt% (e.g., about 0.5 wt% to about 2.5 wt%) quaternary ammonium chloride, a second quaternary ammonium chloride (e.g., about 3.5 wt% to about 4 wt% to about 13 wt%) quaternary ammonium chloride, a second agent, tetraethylammonium bromide), about 0.35 wt.% to about 2.75 wt.% (e.g., about 0.5 wt.% to about 2.5 wt.%) neopentyl glycol, about 5ppm to about 20ppm tin (e.g., SnCl)₂Or any hydrate thereof), and from about 5ppm to about 20ppm indium (e.g., InCl)₃Or any hydrate thereof).

In some embodiments, the one or more quaternary ammonium agents is a salt having formula I.

Wherein

Is saturated, partially unsaturated, or fully unsaturated;

X₁、X₂、X₃、X₄and X₅Each independently of the otherIs selected from carbon, oxygen and nitrogen, with the proviso that X₁、X₂、X₃、X₄And X₅Is nitrogen;

each R is independently hydrogen, alkyl, cycloalkyl, aryl, arylalkyl, heterocycloalkyl, or heteroaryl, wherein each R is independently and optionally halo, -CN, -NO₂、-Q₂、-OQ₂、-S(O)_zQ₂、-S(O)_zN(Q₂)₂、-N(Q₂)₂、-C(O)OQ₂、-C(O)Q₂、-C(O)N(Q₂)₂、-C(O)N(Q₂)(OQ₂)、-N(Q₂)C(O)Q₂、-N(Q₂)C(O)N(Q₂)₂、-N(Q₂)C(O)OQ₂or-N (Q)₂)S(O)_zQ₂Substitution;

each Q₂Independently is hydrogen, alkyl, cycloalkyl, aryl, arylalkyl, heterocycloalkyl, or heteroaryl, each optionally with 1 to 3Q₃Substituent group substitution;

each Q₃Independently is halo, oxo, CN, NO₂、CF₃、OCF₃、OH、-S(O)_z(C_1-6Alkyl), -N (C)_1-6Alkyl radical)₂、-COO(C_1-6Alkyl), -C (O) (C)_1-6Alkyl), -O (C)_1-6Alkyl), or C substituted with 1 to 3 substituents_1-6Alkyl, said 1 to 3 substituents being selected from halo, oxo, -CN, -NO₂、-CF₃、-OCF₃、-OH、-SH、-S(O)_zH、-NH₂or-COOH;

m is 0, 1,2,3,4 or 5;

n is 0, 1 or 2;

z is 0, 1 or 2; and

y is an anion.

In one embodiment, X₁、X₂、X₃、X₄And X₅One or two of which are nitrogen and the others are carbon. In another embodiment, X₁、X₂、X₃、X₄And X₅One of which is nitrogen and the other is carbon. In another embodiment, X₁、X₂、X₃、X₄And X₅Two of which are nitrogen and the others are carbon. In yet another embodiment of the present invention,

selected from pyridine, pyrimidine, pyrazine, piperazine, piperidine, morpholine, 1, 3-oxazinane, 1, 2-oxazinane, pyrrolidine, pyrrole, pyrazole, imidazole, oxazole, isoxazole, 1,2, 3-oxadiazole, 1,3, 4-oxadiazole, 1,2, 3-triazole, 1,2, 4-triazole, 1,2,3, 5-oxatriazole, 1,2,4, 5-oxatriazole and tetrazole.

In one embodiment of the present invention,

selected from pyridine, pyrimidine, pyrazine, piperazine, piperidine, morpholine, 1, 3-oxazinane and 1, 2-oxazinane. In one embodiment of the present invention,

selected from pyridine, pyrimidine and pyrazine. In a further embodiment of the method according to the invention,

is pyridine.

In one embodiment of the present invention,

selected from piperidine, morpholine, 1, 3-oxazinane and 1, 2-oxazinane. In a further embodiment of the method according to the invention,

selected from piperidine and morpholine. In one embodiment of the present invention,

is piperidine. In one embodiment of the present invention,

is morpholine.

In one embodiment of the present invention,

selected from pyrrolidine, pyrrole, pyrazole, imidazole, oxazole, isoxazole, 1,2, 3-oxadiazole, 1,3, 4-oxadiazole, 1,2, 3-triazole, 1,2, 4-triazole, 1,2,3, 4-oxadiazole, 1,2,3, 5-oxadiazole, 1,2,4, 5-oxadiazole and tetrazole. In a further embodiment of the method according to the invention,

selected from the group consisting of pyrrole, pyrazole and imidazole. In one embodiment of the present invention,

is pyrrole. In one embodiment of the present invention,

is pyrazole. In one embodiment of the present invention,

is imidazole. In one embodiment of the present invention,

is pyrrolidine.

In one embodiment, n is 1. In another embodiment, n is 0.

In one embodiment, each R is independently alkyl or cycloalkyl, wherein each R is independently and optionally substituted with halo, -CN, -NO₂、-OQ₂、-S(O)_zQ₂、-S(O)_zN(Q₂)₂、-N(Q₂)₂、-C(O)OQ₂、-C(O)Q₂、-C(O)N(Q₂)₂、-C(O)N(Q₂)(OQ₂)、-N(Q₂)C(O)Q₂、-N(Q₂)C(O)N(Q₂)₂、-N(Q₂)C(O)OQ₂、-N(Q₂)S(O)_zQ₂Or optionally with 1 to 3Q₃Heterocycloalkyl or alkyl substituted by substituentsAnd (4) a base. In another embodiment, each R is independently alkyl or cycloalkyl, wherein each R is independently and optionally halo, heterocycloalkyl, -CN, -NO₂、-OQ₂、-N(Q₂)₂、-C(O)OQ₂、-C(O)Q₂or-C (O) N (Q)₂)₂And (4) substitution. In another embodiment, each R is alkyl, which is independently and optionally substituted with halo, heterocycloalkyl, -CN, -NO₂、-OQ₂、-N(Q₂)₂、-C(O)OQ₂、-C(O)Q₂or-C (O) N (Q)₂)₂And (4) substitution. In yet another embodiment, each R is alkyl, which is independently and optionally substituted with halo, heterocycloalkyl, -CN, -NO₂、-N(Q₂)₂or-C (O) N (Q)₂)₂And (4) substitution. In yet another embodiment, each R is alkyl, which is independently and optionally substituted with halo or heterocycloalkyl.

In another embodiment, each R is alkyl, substituted with heterocycloalkyl. In yet another embodiment, R is alkyl, substituted with pyrrolidine. In yet another embodiment, R is propyl, substituted with heterocycloalkyl. In yet another embodiment, R is propyl, substituted with pyrrolidine.

In one embodiment, each R is unsubstituted alkyl. For example, R is unsubstituted, straight or branched C_1-20An alkyl group. In another embodiment, R is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, dodecyl, and hexadecyl. In one embodiment, R is selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, and hexadecyl. In one embodiment, R is methyl. In one embodiment, R is ethyl. In one embodiment, R is propyl. In one embodiment, R is butyl. In one embodiment, R is pentyl. In one embodiment, R is hexyl. In one embodiment, R is heptyl. In one embodiment, R is octyl. In one embodiment, R is dodecyl. In one embodiment, R is nonyl. In thatIn one embodiment, R is decyl. In one embodiment, R is dodecyl. In one embodiment, R is hexadecyl.

In one embodiment, Y is an anion selected from the group consisting of fluoride, chloride, bromide, iodide, arsenate, phosphate, arsenite, hydrogen phosphate, dihydrogen phosphate, sulfate, nitrate, hydrogen sulfate, nitrite, thiosulfate, sulfite, perchlorate, iodate, chlorate, bromate, chlorite, hypochlorite, chlorate, perchlorate, hypobromite, bromite, bromate, perbromite, carbonate, chromate, bicarbonate (bicarbonate), dichromate, acetate, formate, cyanide, amide, cyanate, peroxide, thiocyanate, oxalate, hydroxide, and permanganate. In another embodiment, Y is a monovalent anion selected from the group consisting of fluoride, chloride, bromide, iodide, dihydrogen phosphate, nitrate, perchlorate, hypochlorite, bicarbonate (bicarbonate), acetate, formate, cyanide, and hydroxide. In yet another embodiment, Y is a divalent anion selected from the group consisting of hydrogen phosphate, sulfate, and carbonate. In yet another embodiment, Y is selected from the group consisting of fluoride, chloride, bromide, and iodide. In one embodiment, Y is chloride. In one embodiment, Y is bromide. In one embodiment, Y is iodide.

In some embodiments, the one or more quaternary ammonium agents is a salt having formula Ia, formula Ib, formula Ic, formula Id, or formula Ie.

Wherein

Each of R, R 'and R "is independently hydrogen, alkyl, cycloalkyl, aryl, arylalkyl, heterocycloalkyl, or heteroaryl, wherein each of R, R' and R" is independently and optionally halo, -CN, -NO₂、-OQ₂、-S(O)_zQ₂、-S(O)_zN(Q₂)₂、-N(Q₂)₂、-C(O)OQ₂、-C(O)Q₂、-C(O)N(Q₂)₂、-C(O)N(Q₂)(OQ₂)、-N(Q₂)C(O)Q₂、-N(Q₂)C(O)N(Q₂)₂、-N(Q₂)C(O)OQ₂、-N(Q₂)S(O)_zQ₂Or optionally with 1 to 3Q₃A substituted heterocycloalkyl or alkyl group;

each Q₂Independently is hydrogen, alkyl, cycloalkyl, aryl, arylalkyl, heterocycloalkyl, or heteroaryl, each optionally substituted with 1 to 3Q₃Substituent group substitution;

each Q₃Independently is halo, oxo, CN, NO₂、CF₃、OCF₃、OH、-S(O)_z(C_1-6Alkyl), -N (C)_1-6Alkyl radical)₂、-COO(C_1-6Alkyl), -C (O) (C)_1-6Alkyl), -O (C)_1-6Alkyl), or C optionally substituted with 1 to 3 substituents_1-6Alkyl, said 1 to 3 substituents being selected from halo, oxo, -CN, -NO₂、-CF₃、-OCF₃、-OH、-SH、-S(O)_zH、-NH₂or-COOH;

z is 0, 1 or 2; and

y is an anion.

In some embodiments of formulas Ia through Ie, each R, R 'and R "is independently alkyl or cycloalkyl, wherein each R, R' and R" is independently and optionally halo, -CN, -NO₂、-OQ₂、-S(O)_zQ₂、-S(O)_zN(Q₂)₂、-N(Q₂)₂、-C(O)OQ₂、-C(O)Q₂、-C(O)N(Q₂)₂、-C(O)N(Q₂)(OQ₂)、-N(Q₂)C(O)Q₂、-N(Q₂)C(O)N(Q₂)₂、-N(Q₂)C(O)OQ₂、-N(Q₂)S(O)_zQ₂Or optionally with 1 to 3Q₃A substituent-substituted heterocycloalkyl or alkyl group. In another embodiment, each of R, R 'and R "is independently an alkyl or cycloalkyl group, wherein each of R, R' and R" is independently andoptionally with halo, heterocycloalkyl, -CN, -NO₂、-OQ₂、-N(Q₂)₂、-C(O)OQ₂、-C(O)Q₂or-C (O) N (Q)₂)₂And (4) substitution. In another embodiment, each of R, R' and R "is independently alkyl, which is independently and optionally substituted with halo, heterocycloalkyl, -CN, -NO₂、-OQ₂、-N(Q₂)₂、-C(O)OQ₂、-C(O)Q₂or-C (O) N (Q)₂)₂And (4) substitution. In yet another embodiment, each of R, R' and R "is independently alkyl, which is independently and optionally substituted with halo, heterocycloalkyl, -CN, -NO₂、-N(Q₂)₂or-C (O) N (Q)₂)₂And (4) substitution.

In one embodiment, each of R, R' and R "is independently an unsubstituted alkyl group. In another embodiment, each of R, R' and R "is independently selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, dodecyl, and hexadecyl. In one embodiment, each R, R' and R "is independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, and hexadecyl.

In some embodiments of formulas Ia through Ie, Y is selected from the group consisting of fluoride, chloride, bromide, iodide, arsenate, phosphate, arsenite, hydrogen phosphate, dihydrogen phosphate, sulfate, nitrate, hydrogen sulfate, nitrite, thiosulfate, sulfite, perchlorate, iodate, chlorate, bromate, chlorite, hypochlorite, hypobromite, carbonate, chromate, bicarbonate (bicarbonate), dichromate, acetate, formate, cyanide, amide, cyanate, peroxide, thiocyanate, oxalate, hydroxide, and permanganate. In another embodiment, Y is a monovalent anion selected from the group consisting of fluoride, chloride, bromide, iodide, dihydrogen phosphate, nitrate, perchlorate, hypochlorite, bicarbonate (bicarbonate), acetate, formate, cyanide, and hydroxide. In yet another embodiment, Y is selected from the group consisting of divalent anions of hydrogen phosphate, sulfate, and carbonate. In yet another embodiment, Y is selected from the group consisting of fluoride, chloride, bromide, and iodide. In one embodiment, Y is chloride. In one embodiment, Y is bromide. In one embodiment, Y is iodide.

In some embodiments of formulas Ia through Ie, k is 0 or 1. In another embodiment, k is 0. In yet another embodiment, k is 1.

In some embodiments of formula Ia, each R and R' is independently selected from methyl, ethyl, butyl, and hexyl. In another embodiment, k is 1; r' is selected from ethyl, butyl and hexyl; and R is methyl. In yet another embodiment, k is 0 and R' is selected from ethyl, butyl, and hexyl.

In one embodiment, the salt of formula Ia is selected from 1-ethyl-3-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, 1-butyl-4-methylpyridinium bromide, and 1-hexylpyridinium bromide.

In some embodiments of formula Ib, each of R, R' and R "is independently selected from methyl and propyl.

In one embodiment, the salt of formula Ib is 1-methyl-1-propylpiperidinium bromide.

In some embodiments of formula Ic, each of R, R' and R "is independently selected from methyl, ethyl, and butyl. In another embodiment, k is 0.

In one embodiment, the salt of formula Ic is selected from N-methyl-N-ethylmorpholine bromide and N-methyl-N-butylmorpholine bromide.

In some embodiments of formula Id, each of R, R' and R "is independently selected from methyl, ethyl, butyl, hexyl, octyl, and decyl. In another embodiment, k is 1 and R is methyl.

In one embodiment, the salt of formula Id is selected from the group consisting of 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-ethyl-2, 3-dimethylimidazolium bromide, 1-decyl-3-methylimidazolium bromide, 1-butyl-2, 3-dimethylimidazolium bromide, 1-methyl-3-octylimidazolium bromide, and 1-methyl-3-hexylimidazolium bromide.

In some embodiments of formula Ie, each of R, R' and R "is independently selected from methyl, ethyl, propyl, butyl, pentyl, and hexyl. In another embodiment, k is 0 and each R' and R "is independently alkyl, optionally substituted with cycloalkyl or halo. In another embodiment, k is 0 and each R 'and R' is independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-chloroethyl, or 3- (methylpyrrolidinium) propyl.

In one embodiment, the salt of formula Ie is selected from N-methyl-N-ethylpyrrolidinium bromide, N-ethyl-N-propylpyrrolidinium bromide, N-propyl-N-butylpyrrolidinium bromide, N-methyl-N-butylpyrrolidinium bromide, N-ethyl-N- (2-chloroethyl) pyrrolidinium bromide, N-methyl-N-hexylpyrrolidinium bromide, N-methyl-N-pentylpyrrolidinium bromide, N-ethyl-N-butylpyrrolidinium bromide, N-butyl-N-pentylpyrrolidinium bromide, N-methyl-N-propylpyrrolidinium bromide, N-ethyl-N-butylpyrrolidinium bromide, N-butyl-N-pentylpyrrolidinium bromide, N-methyl-N-propylpyrrolidinium bromide, or mixtures thereof, Trimethylene-bis (N-methylpyrrolidinium) dibromide, and N-propyl-N-pentylpyrrolidinium bromide.

In some embodiments, the one or more quaternary ammonium agents comprise a compound having formula (la)

The reagent of (1), wherein R₁、R₂、R₃And R₄Each independently hydrogen or an alkyl group (e.g., C)_1-6Alkyl radicals or C_1-4Alkyl group) and Y is an anion as defined herein. In some embodiments, the one or more quaternary ammonium agents include ammonium halides (e.g., NH)₄Br、NH₄Cl or any combination thereof), tetraalkylammonium halides (e.g., tetramethylammonium bromide, tetramethylammonium chloride, triethylmethylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, trimethylpropylammonium bromide, combinations thereof, and the like), heterocyclic ammonium halides (e.g., N-methyl-N-ethylpyrrolidinium chloride, N-ethyl-N-methylpyrrolidinium halide, combinations thereof, and the like), and the like) Or any combination thereof. In some embodiments, the one or more quaternary ammonium agents comprise a quaternary ammonium agent selected from the group consisting of: ammonium chloride, ammonium bromide, tetraethylammonium bromide, trimethylpropylammonium bromide, N-methyl-N-ethylmorpholinium bromide, N-ethyl-N-methylmorpholinium bromide, N-methyl-N-butylmorpholinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N, N, N-triethyl-N-propylammonium bromide, N-ethyl-N-propylpyrrolidinium bromide, N-propyl-N-butylpyrrolidinium bromide, N-methyl-N-butylpyrrolidinium bromide, N-ethyl-N- (2-chloroethyl) pyrrolidinium bromide, N-methyl-N-hexylpyrrolidinium bromide, N-ethylpropylphosphonium bromide, N-N-butylpyrrolidinium bromide, N-ethylphosphonium bromide, N-hexylpyrrolidinium bromide, N-ethylphosphonium bromide, N-hexylpyrrolidinium bromide, N-butylphosphonium bromide, N-propylphosphonium bromide, N-butylphosphonium bromide, N-N-butylphosphonium bromide, or a salt, N-methyl-N-pentylpyrrolidinium bromide, N-ethyl-N-butylpyrrolidinium bromide, trimethylene-bis (N-methylpyrrolidinium) dibromide, N-butyl-N-pentylpyrrolidinium bromide, N-methyl-N-propylpyrrolidinium bromide, N-propyl-N-pentylpyrrolidinium bromide, and any combination thereof. In some examples, the electrolyte comprises from about 1% to about 5% by weight of one or more quaternary ammonium agents. In some examples, the electrolyte comprises from about 3 wt% to about 7 wt% of one or more quaternary ammonium agents. Also, in some embodiments, the one or more quaternary ammonium agents include N-methyl-N-ethylmorpholinium bromide. In other examples, the electrolyte comprises about 0.25 wt% to about 1.25 wt% N-methyl-N-ethylmorpholinium bromide. Also, in some examples, the one or more quaternary ammonium agents include tetraethylammonium bromide, trimethylpropylammonium bromide, or any combination thereof. For example, the electrolyte comprises about 1 wt% to about 5 wt% tetraethylammonium bromide.

In some embodiments, the one or more quaternary ammonium agents comprise a quaternary ammonium agent selected from the group consisting of: ammonium bromide complexing agent, imidazolium bromide complexing agent, pyrrolidinium bromide complexing agent, pyridinium bromide complexing agent, phosphonium bromide complexing agent, and morpholinium bromide complexing agent.

In some examples, the one or more quaternary ammonium agents include a quaternary ammonium agent selected from the group consisting of: tetraethylammonium (TEA) bromide, N-ethyl-N-methylmorpholinium (MEM) bromide, trimethylpropylammonium bromide, 1-ethyl-3-methylimidazolium bromide, 1-butyl-1-methylpyrrolidinium bromide, 1-ethyl-3-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-methyl-1-propylpiperidinium bromide, dodecyltrimethylammonium bromide, 1-ethyl-2, 3-dimethylimidazolium bromide, 1-decyl-3-methylimidazolium bromide, N-ethylmethylmorpholinium (MEM) bromide, N-ethylmorpholinium (MEM) bromide, trimethylpyridinium bromide, N-ethylmorpholinium bromide, 1-3-methylimidazolium bromide, 1-3-methylpyridinium bromide, 1-ethyl-2-1-methylpyridinium bromide, N-1-ethyl-3-methylpyridinium bromide, N-methyl-piperidinium bromide, N-methyl-pyridinium bromide, N-methyl-1-ethyl-2-ethylpyridinium bromide, N-propylpiperidinium bromide, N-methyl-2-N-methyl-1-propylpyridinium bromide, N-methyl-2-methyl pyridinium bromide, N-2-methyl pyridinium bromide, N-1-one, N-one, N-one, N-methyl-one, N-one, N-one, N-one, N-one, N-one, N-one, N-, 1-butyl-2, 3-dimethylimidazolium bromide, 1-methyl-3-octylimidazolium bromide, 1-methyl-3-hexylimidazolium bromide, 1-butyl-3-methylpyridinium bromide, 1-butyl-4-methylpyridinium bromide, 1-hexylpyridinium bromide, triethylmethylammonium chloride, tetraethylphosphonium bromide, 1-methyl-1-propylpyrrolidinium bromide, hexyltrimethylammonium bromide, and hexadecyltriethylammonium bromide.

In some embodiments, the one or more quaternary ammonium agents include 1-ethyl-3-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, or 1-butyl-1-methylpyrrolidinium bromide. For example, the electrolyte comprises about 1 to about 5 weight percent (e.g., about 1.5 to about 4 weight percent) of 1-ethyl-3-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, N-ethyl-N-methylmorpholinium bromide, or 1-butyl-1-methylpyrrolidinium bromide.

In some embodiments, the one or more quaternary ammonium agents comprise a quaternary ammonium compound having the formula N⁺(R^A)(R^B)₃X^-In which R is^AIs C_1-6Alkyl (e.g., methyl, ethyl, propyl, butyl, etc.), R^BIs C_1-6Alkyl (e.g., methyl, ethyl, propyl, butyl, etc.), and X is Br or Cl. In some embodiments, R^BIs different from R^AC of (A)_1-6Alkyl groups and vice versa. In some embodiments, the one or more quaternary ammonium agents are selected from triethylmethylammonium chloride and/or tetraethylammonium chloride.

In some examples, the one or more quaternary ammonium agents include quaternary ammonium agents including at least one of: 1-ethyl-4-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, triethylmethylammonium chloride, 1 '-dioctadecyl-4-4' -bipyridinium dibromide or 1-ethyl-4-methylpyridinium bromide.

In some embodiments, the one or more quaternary ammonium agents comprise cetyl triethylammonium bromide (CTAB), decyl triethylammonium bromide, or dodecyl triethylammonium bromide. For example, the electrolyte comprises about 0.01 wt% to about 1 wt% (e.g., about 0.05 wt% to about 0.5 wt%) cetyltriethylammonium bromide (CTAB).

In some examples, the one or more quaternary ammonium agents include tetraethylammonium bromide, trimethylpropylammonium bromide, or any combination thereof. For example, the electrolyte comprises about 1 wt% to about 6 wt% (e.g., about 1.5 wt% to about 5 wt%) tetraethylammonium bromide. For example, the electrolyte comprises about 1 wt.% to about 5 wt.% (e.g., about 1.5 wt.% to about 3.5 wt.%) trimethylpropylammonium bromide.

Without being bound by theory, it is believed that the quaternary ammonium agent enhances electrochemistry by creating a buoyancy effect with the bromine complex formed with the quaternary ammonium agent. As bromide ions in the electrolyte pseudo-polymerize, they become heavier and sink to the bottom of the electrolyte volume, reducing the dynamic in the cell. Quaternary ammonium agents that create a buoyancy effect help alleviate the problem, thereby taking pseudo-polymeric bromide ions off the bottom of the electrolyte volume and increasing the dynamic in the cell.

In some embodiments, the electrolyte further comprises less than 1 wt% of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, Fe, or any combination thereof. For example, the electrolyte contains less than 1 wt% of Sn and In.

In some embodiments, the electrolyte further comprises about 30 wt% to about 50 wt% water. In some embodiments, the electrolyte further comprises about 35 wt% to about 45 wt% water. In some examples, the water is demineralized until its impedance is greater than about 8 Μ Ω -cm (e.g., about 10 Μ Ω -cm or greater than about 10 Μ Ω -cm). In other examples, the water is only tap water.

In some embodiments, the electrolyte further comprises HBr in an amount sufficient to impart a pH of about 2 to about 4 (about 2.5 to about 3.5) to the electrolyte. In some embodiments, the electrolyte further comprises from about 0.1 wt% to about 2 wt% (e.g., from about 0.3 wt% to about 1 wt%) HBr.

In some embodiments, the electrolyte further comprises about 0.1 wt.% to about 2 wt.% (e.g., about 0.3 wt.% to about 1 wt.%) acetic acid. In alternative embodiments, the electrolyte comprises about 0.1% to about 2% by weight of acetic acid, sodium acetate, potassium acetate, or any combination thereof.

In some embodiments, the electrolyte further comprises about 2% to about 8% (e.g., about 3% to about 5%) by weight of citric acid monohydrate. In some embodiments, the electrolyte further comprises about 2% to about 8% (e.g., about 3% to about 5%) by weight of potassium dihydrogen citrate monohydrate.

In some embodiments, the electrolyte further comprises from about 2 wt% to about 8 wt% (e.g., from about 3 wt% to about 5 wt%) oxalic acid. In some embodiments, the electrolyte further comprises from about 2% to about 8% (about 3% to about 5%) by weight oxalic acid.

In some embodiments, the electrolyte further comprises a stabilizing additive. For example, the stabilizing additive is acetic acid, sodium acetate, oxalic acid, sodium oxalate, citric acid, sodium citrate, 18-crown-6, dicyandiamide, succinic acid, sodium methanesulfonate, sodium propionate, sodium malonate, sodium caproate, sodium hexafluoroaluminate, sebacic acid, potassium trifluoromethanesulfonate, acetonitrile, propionitrile, acquivion ionomer, sodium butyrate, melamine, sebacic acid, 2-bipyridine, dodecanedioic acid, sodium trichloroacetate, dodecanoic acid, sodium dodecanoate, 15-crown-5, or trichloroacetic acid. In some embodiments, the additive enhances electrochemistry. In other embodiments, the additive does not alter the electrochemistry.

In some embodiments, the electrolyte further comprises an antifoaming agent. For example, the electrolyte comprises a polydimethylsiloxane trimethylsiloxy defoamer having a molecular weight (Mn) of about 1000amu to about 2000amu (e.g., about 1000amu to about 1500amu, or 1250 amu). In some examples, the electrolyte comprises about 0.1 wt% to about 0.35 wt% of an antifoaming agent (e.g., a polydimethylsiloxane trimethylsiloxy antifoaming agent having a molecular weight (Mn) of about 1000amu to about 2000amu (e.g., about 1000amu to about 1500amu, or 1250 amu)).

Another aspect of the invention provides an electrolyte for use in a secondary zinc halide electrochemical cell comprising about 30 wt.% to about 40 wt.% ZnBr₂、ZnCl₂Or any combination thereof, about 4 wt% to about 12 wt% KBr, about 4 wt% to about 12 wt% KCl, about 0.5 wt% to about 10 wt% glyme, and about 1 wt% to about 5 wt% of one or more quaternary ammonium agents.

Another aspect of the invention provides an electrolyte for use in a secondary zinc halide electrochemical cell comprising about 30 wt.% to about 40 wt.% ZnBr₂About 4 wt% to about 12 wt% KBr, about 4 wt% to about 12 wt% KCl, about 0.5 wt% to about 10 wt% glyme, and about 1 wt% to about 5 wt% of one or more quaternary ammonium agents.

Another aspect of the invention provides an electrolyte for use in a secondary zinc halide electrochemical cell comprising about 30 wt.% to about 40 wt.% ZnBr₂And about 0.01 wt% to about 0.9 wt% of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, Fe, or any combination thereof.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 wt% to about 15 wt% KBr, about 5 wt% to about 15 wt% KCl, about 0.5 wt% to about 10 wt% of one or more quaternary ammonium agents, about 0.1 wt% to about 2 wt% acetic acid, and about 0.05 wt% to about 4 wt% crown ether.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About, an5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 to about 10 weight percent of one or more quaternary ammonium agents, about 0.1 to about 2 weight percent acetic acid, about 0.05 to about 4 weight percent crown ethers, and wherein the one or more quaternary ammonium agents comprise tetraethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 wt% to about 15 wt% KBr, about 5 wt% to about 15 wt% KCl, about 0.5 wt% to about 10 wt% of one or more quaternary ammonium agents, about 0.1 wt% to about 2 wt% acetic acid, about 0.05 wt% to about 4 wt% crown ether, and wherein the one or more quaternary ammonium agents comprise trimethyl propyl ammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 wt% to about 15 wt% KBr, about 5 wt% to about 15 wt% KCl, about 0.5 wt% to about 10 wt% of one or more quaternary ammonium agents, about 0.1 wt% to about 2 wt% acetic acid, about 0.05 wt% to about 4 wt% crown ethers, and wherein the one or more quaternary ammonium agents include tetraethylammonium bromide, methylethylpyridinium bromide, and hexadecyltrimethylammonium bromide. In another embodiment, the methylethylpyridinium bromide is selected from 1-ethyl-2-methylpyridinium bromide, 1-ethyl-3-methylpyridinium bromide or 1-ethyl-4-methylpyridinium bromide. In another embodiment, the methylethylpyridinium bromide is 1-ethyl-3-methylpyridinium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 to about 10 weight percent of one or more quaternary ammonium agents, about 0.1 to about 2 weight percent acetic acid, about 0.05 to about 4 weight percent crown ethers, and wherein the one or more quaternary ammonium agents include triethylpropylammonium bromide, methylethylpyridinium bromide, and hexadecyltriethylammonium bromide. In another embodiment, the methylethylpyridinium bromide is 1-ethyl-2-methylpyridinium bromideA compound (I) is provided.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 to about 10 weight percent of one or more quaternary ammonium agents, about 0.1 to about 2 weight percent acetic acid, about 0.05 to about 4 weight percent crown ethers, and wherein the one or more quaternary ammonium agents include triethylpropylammonium bromide, 1-butyl-3-methylpyridinium bromide, and hexadecyltriethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 to about 10 weight percent of one or more quaternary ammonium agents, about 0.1 to about 2 weight percent acetic acid, about 0.05 to about 4 weight percent crown ethers, and wherein the one or more quaternary ammonium agents include triethylpropylammonium bromide, 1-ethyl-3-methylpyridinium bromide, and hexadecyltriethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 wt% to about 15 wt% KBr, about 5 wt% to about 15 wt% KCl, about 0.5 wt% to about 10 wt% of one or more quaternary ammonium agents, about 0.1 wt% to about 2 wt% acetic acid, about 0.05 wt% to about 4 wt% crown ethers, and wherein the one or more quaternary ammonium agents include triethylpropylammonium bromide, 1-ethyl-2-methylpyridinium bromide, and hexadecyltriethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 to about 10 weight percent of one or more quaternary ammonium agents, about 0.1 to about 2 weight percent acetic acid, about 0.05 to about 4 weight percent crown ethers, and wherein the one or more quaternary ammonium agents include triethylpropylammonium bromide, 1-ethyl-4-methylpyridinium bromide, and hexadecyltriethylammonium bromide.

In some implementationsIn an example, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 to about 10 weight percent of one or more quaternary ammonium agents, about 0.1 to about 2 weight percent acetic acid, about 0.05 to about 4 weight percent crown ethers, and wherein the one or more quaternary ammonium agents include tetraethylammonium bromide, 1-butyl-3-methylpyridinium bromide, and hexadecyltriethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 wt% to about 15 wt% KBr, about 5 wt% to about 15 wt% KCl, about 0.5 wt% to about 10 wt% of one or more quaternary ammonium agents, about 0.1 wt% to about 2 wt% acetic acid, about 0.05 wt% to about 4 wt% crown ethers, and wherein the one or more quaternary ammonium agents include at least tetraethylammonium bromide, N-ethyl-N-methylmorpholinium bromide, and hexadecyltriethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 to about 10 weight percent of one or more quaternary ammonium agents, about 0.1 to about 2 weight percent acetic acid, about 0.05 to about 4 weight percent crown ethers, and wherein the one or more quaternary ammonium agents include trimethylpropylammonium bromide, 1-butyl-1-methylpyrrolidinium bromide, and hexadecyltriethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 to about 10 weight percent of one or more quaternary ammonium agents, wherein the one or more quaternary ammonium agents comprise tetraethylammonium bromide, methylethylpyridinium bromide, and hexadecyltriethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂About 5 to about 15 weight percent KBr, about 5 to about 15 weight percent KCl, about 0.5 weight percentFrom an amount% to about 10% by weight of one or more quaternary ammonium agents, wherein the one or more quaternary ammonium agents comprise trimethylpropylammonium bromide, 1-butyl-1-methylpyrrolidinium bromide, and hexadecyltriethylammonium bromide.

Method for preparing electrolyte

Another aspect of the invention provides a method of making an electrolyte for use in a secondary zinc halide electrochemical cell comprising mixing ZnBr₂KBr, KCl, water, and one or more quaternary ammonium agents to form a mixture, wherein the mixture comprises about 30 wt% to about 40 wt% ZnBr₂About 4 wt% to about 12 wt% KBr, about 4 wt% to about 12 wt% KCl, about 0.5 wt% to about 10 wt% of one or more quaternary ammonium agents, and about 25 wt% to about 45 wt% water.

Alternatively, the mixture comprises about 30 wt.% to about 40 wt.% ZnBr₂About 8 wt% to about 12 wt% KBr, about 8 wt% to about 14 wt% KCl, about 0.5 wt% to about 10 wt% of one or more quaternary ammonium agents, and about 25 wt% to about 45 wt% water.

In some embodiments, the mixture comprises about 32 wt.% to about 36 wt.% ZnBr₂。

In some embodiments, the mixture comprises about 4% to about 12% (e.g., about 6% to about 10%) by weight potassium bromide (KBr). In some embodiments, the mixture comprises about 8% to about 12% by weight potassium bromide (KBr).

In some embodiments, the mixture comprises from about 4% to about 12% (e.g., from about 6% to about 10%) by weight of potassium chloride (KCl). In some embodiments, the mixture comprises from about 8% to about 14% by weight potassium chloride (KCl). In some embodiments, the mixture comprises from about 11% to about 14% by weight potassium chloride (KCl).

In some embodiments, the mixture comprises about 27% to about 43% (e.g., about 30% to about 40% or about 35% to about 41%) by weight of water.

In some embodiments, the one or more quaternary ammonium agents are salts having formula I

As described herein.

In some embodiments, the one or more quaternary ammonium agents comprise a quaternary ammonium agent selected from the group consisting of: ammonium halides (e.g. NH)₄Br、NH₄Cl or any combination thereof), tetraalkylammonium halides (e.g., tetramethylammonium bromide, tetramethylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, combinations thereof, and the like), heterocyclic ammonium halides (e.g., N-methyl-N-ethylpyrrolidinium chloride, N-ethyl-N-methylpyrrolidinium halide, combinations thereof, and the like), or any combination thereof. In other embodiments, the one or more quaternary ammonium agents include a quaternary ammonium agent selected from the group consisting of: ammonium chloride, tetraethylammonium bromide, trimethylpropylammonium bromide, N-methyl-N-ethylmorpholinium bromide, N-ethyl-N-methylmorpholinium bromide, N-methyl-N-butylmorpholinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N, N, N-triethyl-N-propylammonium bromide, N-ethyl-N-propylpyrrolidinium bromide, N-propyl-N-butylpyrrolidinium bromide, N-methyl-N-butylpyrrolidinium bromide, N-ethyl-N- (2-chloroethyl) pyrrolidinium bromide, N-methyl-N-hexylpyrrolidinium bromide, N-methyl-N-pentylpyrrolidinium bromide, N-ethyl-N-propylmorpholinium bromide, N-ethyl-N- (2-chloroethyl) pyrrolidinium bromide, N-methyl-N-hexylpyrrolidinium bromide, N-methyl-N-pentylpyrrolidinium bromide, N-ethylmorpholinium bromide, N-propylmorpholinium bromide, N-ethylmorpholinium bromide, N-propylpyrrolidinium bromide, or a salt, N-ethyl-N-pentylpyrrolidinium bromide, N-ethyl-N-butylpyrrolidinium bromide, trimethylene-bis (N-methylpyrrolidinium) dibromide, N-butyl-N-pentylpyrrolidinium bromide, N-methyl-N-propylpyrrolidinium bromide, N-propyl-N-pentylpyrrolidinium bromide, and any combination thereof. In some examples, the mixture comprises from about 1% to about 5% by weight of one or more quaternary ammonium agents. Also, in some embodiments, the one or more quaternary ammonium agents include N-methyl-N-ethylmorpholinium bromide. In other examples, the mixture comprises about 0.25% to about 1.25% by weight of N-methyl-N-ethylmorpholinium bromide. And, in some instances,the one or more quaternary ammonium agents include tetraethylammonium bromide, trimethylpropylammonium bromide, or any combination thereof. For example, the electrolyte comprises about 1 wt% to about 5 wt% tetraethylammonium bromide.

In some embodiments, the one or more quaternary ammonium agents comprise a quaternary ammonium agent selected from the group consisting of: tetraethylammonium (TEA) bromide, N-ethyl-N-methylmorpholinium (MEM) bromide, trimethylpropylammonium bromide, 1-ethyl-3-methylimidazolium bromide, 1-butyl-1-methylpyrrolidinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-ethyl-3-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-methyl-1-propylpiperidinium bromide, dodecyltrimethylammonium bromide, 1-ethyl-2, 3-dimethylimidazolium bromide, N-ethylmethylmorpholinium bromide, N-ethylmorpholinium bromide, N-propyltrimethylammonium bromide, N-ethylmorpholinium bromide, N-1-ethylpyridinium bromide, 1-2-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, N-methylpyridinium bromide, 1-2-methylpyridinium bromide, N-methyl-4-pyridinium bromide, N-methyl-1-propylpiperidinium bromide, N-pyridinium bromide, N-methyl pyridinium bromide, N-one, N-methyl pyridinium bromide, N-one, N-one, N-one, N-one, N, 1-decyl-3-methylimidazolium bromide, 1-butyl-2, 3-dimethylimidazolium bromide, 1-methyl-3-octylimidazolium bromide, 1-methyl-3-hexylimidazolium bromide, 1-butyl-3-methylpyridinium bromide, 1-butyl-4-methylpyridinium bromide, 1-hexylpyridinium bromide, tetraethylphosphonium bromide, 1-methyl-1-propylpyrrolidinium bromide, triethylmethylammonium chloride, hexyltrimethylammonium bromide, hexyltrimethylammonium chloride, and hexadecyltriethylammonium bromide. For example, the one or more quaternary ammonium agents include 1-ethyl-3-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, or 1-butyl-1-methylpyrrolidinium bromide. For example, the electrolyte comprises about 1 to about 4 weight percent (e.g., about 1.5 to about 3 weight percent) of 1-ethyl-3-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, or 1-butyl-1-methylpyrrolidinium bromide.

In some embodiments, the one or more quaternary ammonium agents comprise cetyl triethylammonium bromide (CTAB). For example, the electrolyte comprises about 0.05 wt.% to about 1 wt.% (e.g., about 0.1 wt.% to about 0.5 wt.%) cetyltriethylammonium bromide (CTAB).

In some examples, the one or more quaternary ammonium agents include tetraethylammonium bromide, trimethylpropylammonium bromide, or any combination thereof. For example, the electrolyte comprises about 1 wt% to about 5 wt% (e.g., about 1.5 wt% to about 3.5 wt%) tetraethylammonium bromide. For example, the electrolyte comprises about 1 wt.% to about 5 wt.% (e.g., about 1.5 wt.% to about 3.5 wt.%) trimethylpropylammonium bromide.

Some embodiments additionally include mixing glyme with ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agents, and water), wherein the mixture comprises about 0.5 wt% to about 10 wt% (e.g., about 1 wt% to about 7.5 wt%) of glyme. In some examples, the glyme includes monoglyme, diglyme, triglyme, tetraglyme, or any combination thereof. For example, glyme includes tetraglyme. In other examples, the mixture comprises about 1 wt.% to about 5 wt.% tetraglyme.

Some embodiments additionally include mixing DME-PEG with ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agents, water, and/or glyme) to produce a mixture, wherein the mixture comprises from about 0.5 wt% to about 2.5 wt% (e.g., from about 1 wt% to about 2.25 wt%) of MPEG. In some examples, the DME-PEG has an average molecular weight (e.g., number average molecular weight M) of about 350amu to about 3000amu_n). In other examples, the DME-PEG has an average molecular weight (e.g., number average molecular weight M) of about 1200amu to about 3000amu_n). And, in some examples, the mixture further comprises from about 5 wt% to about 10 wt% DME-PEG, wherein the DME-PEG has an average molecular weight (e.g., number average molecular weight Mn) of from about 1500amu to about 2500amu (e.g., about 2000 amu).

Some areEmbodiments additionally include mixing crown ethers with ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agents, water, etc.) to produce a mixture, wherein the mixture comprises from about 0.05 wt% to about 4 wt% of the crown ether. In some examples, the crown ether is 18-crown-6 or 15-crown-5. In some examples, the mixture comprises about 0.1% to about 1% by weight of the crown ether.

Some embodiments additionally include mixing a substantially water-miscible alcohol with the ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agents, water, glyme, and/or DME-PEG) to generate a mixture, wherein the mixture comprises from about 0.1 wt% to about 1.0 wt% of the alcohol. For example, the alcohol includes C_1-4An alcohol. In other examples, the alcohol comprises methanol, ethanol, 1-propanol, isopropanol, 1-butanol, sec-butanol, isobutanol, tert-butanol, or any combination thereof. And in some examples, the mixture further comprises from about 0.25 wt.% to about 0.75 wt.% of t-butanol.

Some embodiments additionally include blend C_1-10Diol and ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agents, water, glyme, DME-PEG, and/or alcohols) to generate a mixture, wherein the mixture comprises about 0.25 wt% to about 5 wt% (e.g., about 0.5 wt% to about 4 wt%) of C_1-10A diol. In some examples, the diol comprises ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, hexanediol, or any combination thereof. And, in some examples, the mixture comprises from about 0.25% to about 2.5% by weight neopentyl glycol.

Some embodiments additionally include mixing one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, or Fe with ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agent, water, glyme, DME-PEG, alcohol, and/or C)_1-10Glycols) wherein the mixture comprises less than 1 wt% of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn or Fe. For example, the mixture contains less than 1 wt% Sn and In.

Some embodiments additionally include adding a sufficient amount of HBr to the mixture to impart a pH of about 2 to about 4 (about 2.5 to about 3.5) to the mixture.

Some embodiments additionally include mixing acetic acid with ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agents, water, etc.) to produce a mixture, wherein the mixture comprises from about 0.1 wt% to about 2 wt% (e.g., from about 0.3 wt% to about 1 wt%) acetic acid.

Some embodiments additionally include mixing citric acid monohydrate with ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agents, water, etc.) to produce a mixture, wherein the mixture comprises from about 2% to about 8% (e.g., from about 3% to about 5%) by weight of citric acid monohydrate.

Some embodiments additionally include mixing monopotassium citrate monohydrate with ZnBr₂And other ingredients (e.g., KBr, KCl, quaternary ammonium agents, water, etc.) to produce a mixture, wherein the mixture comprises from about 2% to about 8% (e.g., from about 3% to about 5%) by weight of potassium dihydrogen citrate monohydrate.

In some embodiments, for ZnBr₂KBr, KCl, water, and one or more quaternary ammonium agents are mixed at a temperature of about 15 ℃ to about 30 ℃ (e.g., room temperature).

In some embodiments, for ZnBr₂The KBr, KCl, water, and one or more quaternary ammonium agents are mixed with agitation (e.g., stirring the mixture).

In some embodiments, the mixture described herein is optionally filtered. In some embodiments, the mixture described herein is filtered. In some embodiments, the mixture described herein is not filtered.

Another aspect of the invention provides an electrolyte for use in a secondary zinc-bromine electrochemical cell comprising about 25 wt.% to about 45 wt.% ZnBr₂From about 25 wt% to about 45 wt% water, and from 1 wt% to about 25 wt% of an aggregating amount of one or more quaternary ammonium agents, wherein the one or more quaternary ammonium agents comprise at least triethylmethylammonium bromide.

In some embodiments, the electrolyte comprises about 30 wt% to about 40 wt% ZnBr₂. In other embodiments, the electrolyte comprises about 32 wt% to about 38 wt% ZnBr₂。

In some embodiments, the electrolyte comprises from about 35 wt% to about 45 wt% water.

In some embodiments, the electrolyte comprises about 1 wt% to about 5 wt% KBr. For example, the electrolyte comprises about 1.5 wt% to about 4.5 wt% KBr.

In some embodiments, the electrolyte comprises from about 5 wt% to about 15 wt% KCl.

In some embodiments, the electrolyte comprises from about 0.5 wt% to about 2.5 wt% of an ether selected from DME-PEG, dimethyl ether, or any combination thereof. In some examples, the ether is DME-PEG, and the DME-PEG has an average molecular weight of about 350amu to about 3000 amu. In other examples, the DME-PEG has an average molecular weight of about 750amu to about 2500 amu. In some embodiments, the ether is DME-PEG, and the electrolyte comprises from about 0.1 wt% to about 0.5 wt% DME-PEG having an average molecular weight of from about 750amu to about 1250 amu. In other embodiments, the ether is DME-PEG, and the electrolyte comprises from about 1.0 wt% to about 2.0 wt% DME-PEG having an average molecular weight of from about 1750amu to about 2250 amu. And, in some examples, the ether is DME-PEG, the electrolyte comprises from about 0.1% to about 0.5% by weight DME-PEG having an average molecular weight of from about 750amu to about 1250amu, and the electrolyte further comprises from about 1% to about 2% by weight DME-PEG having an average molecular weight of from about 1750amu to about 2250 amu.

In some embodiments, the electrolyte of claim 1 further comprises about 1% to about 10% by weight triethylmethylammonium bromide. For example, the electrolyte comprises about 1.5 wt.% to about 7.5 wt.% triethylammonium bromide.

In some embodiments, the one or more quaternary ammonium agents further comprise at least one quaternary ammonium agent selected from the group consisting of: ammonium chloride, tetraethylammonium bromide, trimethylpropylammonium bromide, N-methyl-N-ethylmorpholinium bromide (MEMBr), N-methyl-N-butylmorpholinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N, N, N-triethyl-N-propylammonium bromide, N-ethyl-N-propylpyrrolidinium bromide, N-propyl-N-butylpyrrolidinium bromide, N-methyl-N-butylpyrrolidinium bromide, 1-methyl-1-butylpyrrolidinium bromide, N-ethyl-N- (2-chloroethylene) pyrrolidinium bromide, N-methyl-N-hexylpyrrolidinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N-ethyl-N- (2-chloroethylene) pyrrolidinium bromide, N-methyl-N-hexylpyrrolidinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N-propylphosphonium bromide, N-propylphosphonium bromide, and a, N-methyl-N-pentylpyrrolidinium bromide, N-ethyl-N-butylpyrrolidinium bromide, trimethylene-bis (N-methylpyrrolidinium) dibromide, N-butyl-N-pentylpyrrolidinium bromide, N-methyl-N-propylpyrrolidinium bromide, N-propyl-N-pentylpyrrolidinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, and cetyltrimethylammonium bromide.

In an alternative embodiment, the one or more quaternary ammonium agents further comprise at least one quaternary ammonium agent selected from the group consisting of: 1-ethyl-4-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide and 1-butyl-3-methylpyridinium bromide. For example, the one or more quaternary ammonium agents additionally comprise 1-ethyl-2-methylpyridinium bromide, and the electrolyte further comprises from about 1.0% to about 10% by weight of 1-ethyl-2-methylpyridinium bromide.

In some embodiments, the one or more quaternary ammonium agents additionally comprise cetyltrimethylammonium bromide, and the electrolyte further comprises about 0.05 wt% to about 0.10 wt% cetyltrimethylammonium bromide.

In some embodiments, the electrolyte comprises an acid or a conjugate base of an acid selected from acetic acid, nitric acid, and citric acid. For example, the electrolyte comprises from about 0.1 wt% to about 1.0 wt% glacial acetic acid. In other examples, the electrolyte comprises from about 0.1 wt% to about 1.0 wt% HBr. In other examples, the electrolyte comprises from about 0.12 wt% to about 0.08 wt% nitric acid. In some examples, the electrolyte comprises about 3.5 wt% to about 4.5 wt% citric acid. And in some examples, the electrolyte comprises about 3.5 wt% to about 4.5 wt% monopotassium citrate.

Another aspect of the invention provides an electrolyte for use in a secondary zinc halide electrochemical cell comprising about 25 wt.% to about 45 wt.% ZnBr₂About 25 to about 45 weight percent water, about 1 to about 5 weight percent KBr, about 5 to about 15 weight percent KCl, and about 1 to about 10 weight percent triethylmethylammonium bromide.

In some embodiments, the electrolyte comprises from about 0.1% to about 1.0% by weight of glacial acetic acid.

In some embodiments, the electrolyte comprises from about 1.0 wt% to about 10 wt% of at least a quaternary ammonium agent selected from the group consisting of: 1-ethyl-4-methylpyridinium bromide, 1-ethyl-2-methylpyridinium ammonium bromide, and 1-butyl-3-methylpyridinium bromide.

In some embodiments, the electrolyte comprises about 0.05 wt% to about 0.10 wt% cetyltrimethylammonium bromide.

In another aspect of the invention, there is provided a method of preparing an electrolyte for use in a secondary zinc halide electrochemical cell comprising mixing ZnBr under aqueous conditions₂KBr, KCl, and triethylmethylammonium bromide to produce a mixture and stirring the mixture until the solids have dissolved, wherein the mixture comprises about 25 wt% to about 45 wt% ZnBr₂About 25 to about 45 weight percent water, about 1 to about 5 weight percent KBr, about 5 to about 15 weight percent KCl, and about 1 to about 110% by weight of triethylmethylammonium bromide.

B. Accumulator battery

Referring to fig. 18-20, another aspect of the invention provides a battery pack comprising a plurality of bipolar electrodes at least partially disposed in a zinc-halogen electrolyte and interposed between a cathode terminal assembly and an anode terminal assembly. The cathode terminal assembly, anode terminal assembly, zinc-halogen electrolyte, and bipolar electrode include any of the embodiments described herein.

1. Frame member

In some embodiments, the battery or electrochemical cell of the present invention includes a frame member 114 between two adjacent bipolar electrodes or between a bipolar electrode and a terminal assembly (e.g., a terminal anode assembly or a terminal cathode assembly).

In one embodiment shown in fig. 23, the frame member has an outer peripheral edge 604 and an inner peripheral edge 608 defining an open interior region 606. The inner peripheral edge 608 defines an open interior area such that the cathode assembly of the bipolar electrode is immediately adjacent to the inner surface of the terminal end plate or the rear surface of the adjacent bipolar electrode plate without interference or obstruction by the frame member. Thus, the open interior region is at least as large as the electrochemically active area of the terminal end plate and at least as large as the reduced surface of the pocket portion of the cathode holder of the cathode assembly. In some embodiments, the frame member is configured such that the open interior region is approximately centered about a center of an electrochemically active area of a terminal end plate received by the frame member and/or a center of a cathode assembly disposed on a bipolar electrode plate of the bipolar electrode. In some embodiments, the outer perimeter of the frame member defines the outer surface of the battery pack or electrochemical cell.

In some embodiments, the frame member includes a first side 614 opposing and securing the first bipolar plate or terminal end plate, and a second side 616 disposed on an opposite side of the frame member from the first side, the second side 616 opposing and securing the second bipolar plate. The first and second electrode plates and the terminal end plate may be configured to have substantially the same size and shape.

In some embodiments, each side of the frame member includes a sealing groove 612 extending around the inner perimeter edge. In some examples, each sealing groove is sized and shaped to conform to a contour of a peripheral edge of a corresponding bipolar electrode plate or terminal end plate secured by the frame member. Also, in some embodiments, each seal groove is configured to receive a seal 116 (fig. 21) (e.g., an O-ring or gasket) seated therein that forms a substantially leak-free seal when the seal is compressed between the corresponding electrode plate or end plate and the frame member when the electrochemical cell or battery is assembled, thereby providing a sealing interface between the electrode plate or end plate and the frame member. The seals cooperate to secure electrolyte between the opposing electrode plates and the frame member or between the electrode plates, end plates, and the frame.

In some embodiments, the frame member has one or more stationary fences 610 that protrude into the open interior area and limit the movement of the pressure plate 105 or electrode plates when the battery is assembled. In other embodiments, one or more fixed fences may extend from the inner perimeter edge into the interior region. In some examples, the securing fence is operable for contacting a generally flat surface of the cathode holder (e.g., a pocket portion of the cathode holder) that projects away from the front surface of the electrode plate in a direction toward the frame member. The fixing fence may reduce or prevent the cathode holder from being bent and deformed from flat during charging of the battery module. The fixed barrier may include openings or cutouts to reduce the overall weight of the frame.

Each frame member may be formed from flame retardant polypropylene fibers, glass fiber filled polypropylene, flame retardant high density polyethylene (e.g., filled or unfilled), or polyvinyl fluoride. Each frame member may receive two adjacent electrode plates or an electrode plate and a terminal end plate. Also, one of the electrode plates may include a surface joined to a cathode assembly having a carbon material and a separator arranged in a layered configuration, and a cathode holder surrounding the carbon material and the separator. Each frame may also contain an aqueous electrolyte solution (e.g., a zinc-halide electrolyte or a zinc-bromide electrolyte). As shown in fig. 19, the frame member disposed adjacent to the platen may optionally include one or more pressure relief valves or rupture discs to relieve excess pressure within the electrochemical cell or battery pack. In some embodiments, the pressure relief valve includes a molded carrier configured to extend through the frame and the pressure relief umbrella or rupture disk (e.g., a rupture disk that ruptures at a pressure of about 300psi or greater).

2. Pressing plate

In some embodiments, the electrochemical cell or battery pack includes a pair of

platens

105, 105a, 105b located at the ends of the electrochemical cell or battery pack. In some embodiments, each platen includes an exterior surface 512 and an interior surface 504 disposed on opposite sides of the platen, distinct from the exterior surface, and opposite the adjacent frame members. Fig. 22 shows the exterior surface of the platen associated with the positive (+) anode terminal of an electrochemical cell or battery and the interior surface of the platen associated with the negative (-) cathode of an electrochemical cell or battery. In some embodiments, the platens are formed from 6061-T6 aluminum and may be manufactured by stamping. In other embodiments, the platen is formed of stainless steel and may be manufactured by machining. Also, in some embodiments, the platen is formed of milled steel.

In some embodiments,

terminal holes

502a, 502b extend through each pressure plate to expose corresponding terminals for electrical connection with connection/power cables. In some embodiments, the platen has a through hole formed therethrough operable for receiving one or more frame bolts or tie rods 120. For example, a first row of four (4) through-holes may be spaced apart (e.g., evenly spaced apart) along the top edge of each platen, while a second row of four (4) through-holes may be spaced apart (e.g., evenly spaced apart) along the bottom edge of each platen.

The outer surface of each platen may include a cutout 508 to reduce the weight of the platen and to define a reinforcement member that reduces stress concentrations when the platen contacts an adjacent terminal frame member. In addition, the cutouts may dissipate heat generated by the electrochemical cells or battery pack. The exterior surface and the cutout may define one or more channels 510 operable for receiving and routing connection/power cables electrically connected with the exposed terminals and/or wiring harnesses for the assembled battery module. Also, in some embodiments, each interior surface of the platen has one or more cutouts.

In some embodiments, the interior surface of each platen may include a generally planar surface operable for engaging an exterior surface of an adjacent frame member. In some embodiments, the interior surface of each platen further defines a recessed area having a size and shape configured to receive at least a portion of an electrically conductive cup-shaped member engaged to and protruding from a terminal end plate associated with a corresponding adjacent platen. In some embodiments, apertures may extend through the inner and outer surfaces of the platen end plate in place of the recessed areas to expose at least a portion of the conductive cup-shaped members and terminals.

In some embodiments of the electrochemical cells or batteries of the invention, each frame member and each pair of compression plates have corresponding through-holes configured to receive bolts or tie rods therethrough and serve to compress these components with fasteners (e.g., nuts 108 and/or washers 106, 110) to assemble a substantially sealed electrochemical cell or battery.

In some embodiments, each frame member, each pressure plate, each terminal end plate, and each bipolar electrode plate has one or more corresponding through-holes that serve as alignment features such that the terminals, conductive cup members, cathode assemblies, and electrochemically active areas share the same approximate center when locating pins 112 are placed therein.

In some embodiments, the battery pack includes a first bipolar electrode, a second bipolar electrode, and a frame member 114, wherein the frame member is interposed between the first bipolar electrode, the frame member has a first side and a second side, the first bipolar electrode has a first electrode plate, and the second bipolar electrode has a second electrode plate; and wherein the first side of the frame member is configured to receive at least a portion of the front side of the first electrode plate and the second side of the frame member is configured to receive at least a portion of the back side of the second electrode plate.

Referring to fig. 19 and 20, another aspect of the invention provides a bipolar battery pack defining a longitudinal axis L, the bipolar battery 1000 comprising a pair of terminal assemblies 104 at respective proximal and distal ends of the battery, each terminal assembly comprising an electrically conductive cup-shaped member 310 comprising a terminal wall 312, a side wall 304, and a rim 306 spaced from the terminal wall by the side wall; and a terminal end plate 302 having an outer surface 316 and an inner surface 318 coplanar with the terminal walls and joining corresponding edges at the outward facing surfaces, the joining enabling bi-directional uniform current flow between the corresponding terminal 308 and the end plate through the cup-shaped member when the corresponding terminal wall is in electrical contact with the corresponding terminal. In some embodiments, the terminal assembly corresponds to the terminal assembly 104 described above with reference to fig. 12-17. In some embodiments, battery pack 1000 further includes at least one pair of middle bipolar electrodes 102, 102' arranged in a parallel orientation between a pair of terminal assemblies. In these embodiments, the intermediate cell includes bipolar electrodes for distributing current between the terminal assemblies. Each intermediate cell includes a frame member 114 that houses the components of the cell.

Fig. 20 provides an exploded view of the battery pack of fig. 19. In some embodiments, each battery pack or electrochemical cell further includes a

corresponding pressure plate

105a, 105b opposite and releasably secured in contact with an outer surface of the end plate 302, each pressure plate including an

aperture

502a, 502b configured to receive a corresponding terminal 308. In some of these embodiments, at least a portion of the terminal wall of the conductive cup-shaped member is exposed through the aperture of the pressure plate. In other embodiments, at least a portion of the terminal walls and sidewalls are exposed through an aperture of the pressure plate. FIG. 7 shows a platen having its corresponding aperture formed therethrough. In other embodiments, a recessed area may be provided at an inward-facing surface of each platen that is configured to receive a corresponding cup-shaped member. In these embodiments, terminal holes may be formed through the recessed area of each pressure plate to expose the terminals. In some embodiments, the outward/exterior surface of the platen includes cutouts to reduce the overall weight of the platen and to help dissipate heat generated by the cells.

In some embodiments, the pressure plates include openings operable to receive tie rods and/or bolts secured by fasteners to compress the two pressure plates and center the frame members together along the longitudinal axis L (fig. 19) when the battery pack is assembled.

In some embodiments, the electrochemically active area of each corresponding terminal end plate includes a first surface area surrounded by the corresponding edge and a remaining second surface area outside an outer periphery of the corresponding edge, the first and second surface areas being substantially equal.

In some embodiments, each terminal wall projects away from an outward surface of the corresponding end plate.

In some embodiments, one of the terminal walls projects away from the outward surface of the corresponding end plate in a proximal direction along the longitudinal axis, while the other terminal wall projects away from the outward surface of the corresponding end plate in an opposite distal direction along the longitudinal axis.

In some embodiments, the terminal walls of the electrically conductive cup-shaped member are exposed at a corresponding one of the proximal and distal ends of the electrochemical cell assembly.

In some embodiments, one of the terminal assemblies in the battery or electrochemical cell further comprises a cathode assembly 202 disposed on an inner surface of a corresponding end plate on a side opposite the corresponding electrically conductive cup-shaped member, the cathode assembly being interposed between the inner surface of the end plate and the back surface of an adjacent bipolar electrode plate.

In some embodiments, each edge is centered within the electrochemically active area of the corresponding end plate.

In some embodiments, each edge of the electrically conductive cup-shaped member is joined to the outward facing surface of the corresponding end plate by welding or adhesive. In some examples, the adhesive is electrically conductive.

In some embodiments, at least one of the conductive cup-shaped member or the terminal end plate comprises a copper/titanium cladding.

In some embodiments, the interior surface of at least one of the electrically conductive cup-shaped members comprises copper. In other embodiments, the outer surface of at least one of the electrically-conductive cup-shaped members comprises titanium.

In some embodiments, each corresponding terminal contacts a central location of the corresponding terminal wall.

In some embodiments, the rim includes a flange extending radially outward from the sidewall.

IV. examples

EXAMPLE 1A-electrolyte formulation

The components used in the electrolyte formulations described below are reagent grade.

Table 1: composition for electrolyte composition

The electrolyte of the present invention was prepared as follows:

table 2: electrolyte formulations No. 1-1 (base formulations).

Electrolytes No. 1-1 produced a cloudy mixture that was not filtered.

Electrolytes No. 1-2 were formulated with the same ingredients in the same amounts, but the electrolytes were filtered prior to testing.

Table 3: electrolyte formulations No. 1-3.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.82
			Water (W)	95	38.92
KBr	21	8.60
			KCl	20	8.19
Acetic acid	1.11	0.45
			1-Ethyl-2-methylpyridinium bromide	4.96	2.03
Tetraethyl ammonium bromide	6.1	2.50
			18-crown-6	0.55	0.23
Cetyl trimethyl ammonium Bromide	0.4	0.16
			Citric acid	10	4.10
Totaling:	244.12	100.00

table 4: electrolyte formulations No. 1-4.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	35.63
			Water (I)	95	39.82
KBr	21	8.80
			KCl	20	8.38
Acetic acid	1.11	0.47
			1-Ethyl-2-methylpyridinium bromide	4.96	2.08
Tetraethyl ammonium bromide	6.1	2.56
			DME-PEG 2000	4	1.68
DME-PEG 2000	1	0.42
			Cetyl trimethyl ammonium Bromide	0.4	0.17
Totaling:	238.57	100.00

test electrolyte formulation No. 3 was prepared as a filtered and unfiltered mixture.

Table 5: electrolyte formulations No. 1-5.

Composition (I)	Quantity (g)	By weight%
			ZnBr₂	101.3	36.78
Water (W)	100	36.31
			KBr	23.8	8.64
KCl	37.2	13.51
			Acetic acid	1.11	0.40
1-Ethyl-2-methylpyridinium bromide	4.96	1.80
			Tetraethyl ammonium bromide	6.1	2.21
18-crown-6	0.55	0.20
			Cetyl trimethyl ammonium Bromide	0.4	0.15
Totaling:	275.42	100

table 6: electrolyte formulations No. 1-6.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	36.31
			Water (W)	95	40.58
KBr	21	8.97
			KCl	20	8.54
Acetic acid	1.11	0.47
			1-butyl-1-methylpyridinium bromide	4.96	2.12
Trimethylpropylammonium bromide	6.1	2.61
			18-crown-6	0.55	0.23
Cetyl trimethyl ammonium Bromide	0.4	0.17
			Totaling:	234.12	100.00

table 7: electrolyte formulations No. 1-7.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.88
			Water (W)	95	38.98
KBr	21	8.62
			KCl	20	8.21
Acetic acid	1.11	0.46
			1-butyl-1-methylpyridinium bromide	4.96	2.04
Trimethylpropylammonium bromide	6.1	2.50
			18-crown-6	0.55	0.23
Citric acid potassium dihydrogen	10	4.10
			Totaling:	243.72	100.00

table 8: electrolyte formulations No. 1-8.

Table 9: electrolyte formulations No. 1-9.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	36.25
			Water (W)	95	40.52
KBr	21	8.96
			KCl	20	8.53
Acetic Acid (AA)	1.11	0.47
			1-Ethyl-2-methylpyridinium bromide	4.96	2.12
Tetraethyl ammonium bromide	6.1	2.60
			18-crown-6	1.1	0.47
Cetyl trimethyl ammonium Bromide	0.2	0.09
			Totaling:	234.47	100.00

table 10: electrolyte formulations No. 1-10.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.70
			Water (W)	95	38.78
KBr	21	8.57
			KCl	20	8.16
Acetic acid	1.11	0.45
			1-Ethyl-2-methylpyridinium bromide	9.92	4.05
Tetraethyl ammonium bromide	12.2	4.98
			18-crown-6	0.55	0.22
Cetyl trimethyl ammonium Bromide	0.2	0.08
			Totaling:	244.98	100.00

table 11: electrolyte formulations No. 1-11.

Table 12: electrolyte formulations No. 1-12.

Composition (I)	Quantity (g)	Weight percent
			ZnBr
₂	85	36.34
			Water (W)	95	40.61
KBr	21	8.98
			KCl	20	8.55
Acetic acid	1.11	0.47
			1-butyl-3-methylpyridinium bromide	4.96	2.12
Tetraethyl ammonium bromide	6.1	2.61
			18-crown-6	0.55	0.24
Cetyl trimethyl ammonium Bromide	0.2	0.09
			Totaling:	233.92	100.00

table 13: electrolyte formulations No. 1-13.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	36.34
			Water (W)	95	40.61
KBr	21	8.98
			KCl	20	8.55
Acetic acid	1.11	0.47
			N-ethyl-N-methylmorpholinium bromide	4.96	2.12
Tetraethyl ammonium bromide	6.1	2.61
			18-crown-6	0.55	0.24
Cetyl trimethyl ammonium Bromide	0.2	0.09
			Totaling:	233.92	100.00

table 14: electrolyte formulations No. 1-14.

Table 15: electrolyte formulations No. 1-15.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	35.29
			Water (W)	95	39.44
KBr	21	8.72
			KCl	20	8.30
Acetic acid	1.11	0.46
			1-butyl-3-methylpyridinium bromide	4.96	2.06
Trimethylpropylammonium bromide	6.1	2.53
			18-crown-6	1.1	0.46
Cetyl trimethyl ammonium Bromide	0.2	0.08
			Tetraethyl ammonium bromide	6.1	2.53
15-crown-5	0.29	0.12
			Totaling:	240.86	100.00

table 16: electrolyte formulations No. 1-16.

Composition (A)	Quantity (g)	By weight%
			ZnBr
₂	85	34.69
			Water (W)	95	38.77
KBr	21	8.57
			KCl	20	8.16
Acetic Acid (AA)	1.11	0.45
			1-Ethyl-2-methylpyridinium bromide	9.92	4.05
Tetraethyl ammonium bromide	12.2	4.98
			18-crown-6	0.55	0.22
Hexadecyl trimethyl ammonium bromide	0.2	0.08
			SnCl₂·2H₂O	About 0.0047	About 0.0019
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from solution)	About 0.026	About 0.0106
Totaling:	about 240.86	About 100.00

Table 17: electrolyte formulations No. 1-17.

Table 18: electrolyte formulations No. 1-18.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.00
			Water (W)	95	38.00
KBr	21	8.40
			KCl	20	8.00
Acetic acid	1.11	0.44
			1-Ethyl-2-methylpyridinium bromide	9.92	3.97
Tetraethyl ammonium bromide	12.2	4.88
			18-crown-6	0.55	0.22
DME-PEG 2000	4	1.60
			DME-PEG 1000	1	0.40
Cetyl trimethyl ammonium Bromide	0.2	0.08
			SnCl₂·2H₂O	About 0.0047	About 0.0019
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from)Solutions)	About 0.026	About 0.0104
Totaling:	about 250.01	About 100.00

Table 19: electrolyte formulations No. 1-19.

Table 20: electrolyte formulations No. 1-20.

Composition (I)	Quantity (g)	By weight%
			ZnBr₂	77.3	32.33
Water (W)	95	39.73
			ZnCl₂	4.68	1.96
KCl	33.2	13.89
			Acetic acid	1.11	0.46
1-Ethyl-2-methylpyridinium bromide	9.92	4.15
			Tetraethyl ammonium bromide	12.2	5.10
18-crown-6	0.55	0.23
			DME-PEG 2000	4	1.67
DME-PEG 1000	1	0.42
			Cetyl trimethyl ammonium Bromide	0.1	0.04
SnCl₂·2H₂O	About 0.0047	About 0.0020
			In (In nitric acid solution)	About 0.0025	About 0.0010
Nitric acid (from solution)	About 0.026	About 0.0109
			Totaling:	about 239.09	About 100.00

Table 21: electrolyte formulations No. 1-21.

Composition (I)	Quantity (g)	By weight%
			ZnBr₂	67.5	28.70
Water (I)	95	40.39
			ZnCl₂	10.6	4.51
KCl	33.2	14.12
			Acetic acid	1.11	0.47
1-Ethyl-2-methylpyridinium bromide	9.92	4.22
			Tetraethyl ammonium bromide	12.2	5.19
18-crown-6	0.55	0.23
			DME-PEG 2000	4	1.70
DME-PEG 1000	1	0.43
			Cetyl trimethyl ammonium Bromide	0.1	0.04
SnCl₂·2H₂O	About 0.0047	About 0.0020
			In (In nitric acid solution)	About 0.0025	About 0.0011
Nitric acid (from solution)	About 0.026	About 0.0111
			Totaling:	about 235.21	About 100.00

Table 22: electrolyte formulations No. 1-22.

Table 23: electrolyte formulations No. 1-23.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	32.92
			Water (W)	95	36.80
KBr	21	8.13
			KCl	20	7.75
Acetic acid	1.11	0.43
			1-Ethyl-2-methylpyridinium bromide	14.88	5.77
Tetraethyl ammonium bromide	18.3	7.09
			18-crown-6	2.75	1.07
Cetyl trimethyl ammonium Bromide	0.1	0.04
			SnCl₂·2H₂O	About 0.0047	About 0.0018
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from solution)	About 0.026	About 0.0101
Totaling:	about 258.17	About 100.00

Table 24: electrolyte formulations No. 1-24.

Table 25: electrolyte formulations No. 1-25.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.40
			Water (W)	95	38.44
KBr	21	8.50
			KCl	20	8.09
Acetic acid	1.11	0.45
			1-Ethyl-2-methylpyridinium bromide	7.92	3.21
Tetraethyl ammonium bromide	14.2	5.75
			18-crown-6	2.75	1.11
Hexadecyl trimethyl ammonium bromide	0.1	0.04
			SnCl₂·2H₂O	About 0.0047	About 0.0019
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from solution)	About 0.026	About 0.0105
Totaling:	about 247.11	About 100.00

Table 26: electrolyte formulations No. 1-26.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.40
			Water (W)	95	38.44
KBr	21	8.50
			KCl	20	8.09
Acetic acid	1.11	0.45
			1-Ethyl-2-methylpyridinium bromide	9.92	4.01
Tetraethyl ammonium bromide	12.2	4.94
			18-crown-6	2.75	1.11
Cetyl trimethyl ammonium Bromide	0.1	0.04
			SnCl₂·2H₂O	About 0.0047	About 0.0019
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from solution)	About 0.026	About 0.0105
Totaling:	about 247.11	About 100.00

Table 27: electrolyte formulations No. 1-27.

Table 28: electrolyte formulations No. 1-28.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	36.37
			Water (I)	95	40.65
KBr	21	8.99
			KCl	20	8.56
Acetic acid	1.11	0.47
			1-Ethyl-2-methylpyridinium bromide	9.92	4.24
Tetraethylphosphonium bromide	1	0.43
			18-crown-6	0.55	0.24
Cetyl trimethyl ammonium Bromide	0.1	0.04
			SnCl₂·2H₂O	About 0.0047	About 0.0020
In (In nitric acid solution)	About 0.0025	About 0.0011
			Nitric acid (from solution)	About 0.026	About 0.0111
Totaling:	about 233.71	About 100.00

Table 29: electrolyte formulations No. 1-29.

Composition (I)	Quantity (g)	Weight percent
			ZnBr
₂	85	34.79
			Water (W)	95	38.89
KBr	21	8.60
			KCl	20	8.19
Propionic acid	0.5	0.20
			1-Ethyl-2-methylpyridinium bromide	9.92	4.06
Tetraethyl phosphonium bromide	12.2	4.99
			18-crown-6	0.55	0.23
Cetyl trimethyl ammonium Bromide	0.1	0.04
			SnCl₂·2H₂O	About 0.0047	About 0.0019
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from solution)	About 0.026	About 0.0106
Totaling:	about 244.30	About 100.00

Table 30: electrolyte formulations No. 1-30.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.68
			Water (W)	95	38.76
KBr	21	8.57
			KCl	20	8.16
Zinc acetate	1.32	0.54
			1-Ethyl-2-methylpyridinium bromide	9.92	4.05
Tetraethyl phosphonium bromide	12.2	4.98
			18-crown-6	0.55	0.22
Cetyl trimethyl ammonium Bromide	0.1	0.04
			SnCl₂·2H₂O	About 0.0047	About 0.0019
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from solution)	About 0.026	About 0.0106
Totaling:	about 245.12	About 100.00

Table 31: electrolyte formulations No. 1-31.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.71
			Water (W)	95	38.79
KBr	21	8.57
			KCl	20	8.17
Acetic acid	1.11	0.45
			1-Ethyl-4-methylpyridinium bromide	9.92	4.05
Tetraethylphosphonium bromide	12.2	4.98
			18-crown-6	0.55	0.22
Cetyl trimethyl ammonium Bromide	0.1	0.04
			SnCl₂·2H₂O	About 0.0047	About 0.0019
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from solution)	About 0.026	About 0.0106
Totaling:	about 244.91	About 100.00

Table 32: electrolyte formulations No. 1-32.

Table 33: electrolyte formulations No. 1-33.

Composition (I)	Quantity (g)	Weight percent
			ZnBr
₂	85	34.89
			Water (W)	95	39.00
KBr	5.3	2.18
			KCl	29.8	12.23
HBr	1.17	0.48
			1-Ethyl-2-methylpyridinium bromide	9.92	4.07
Triethyl methyl ammonium Bromide	12.2	5.01
			Cetyl trimethyl ammonium Bromide	0.2	0.08
mPEG-2K	4	1.64
			mPEG-1K	1	0.41
Totaling:	about 243.59	About 100.00

Table 34: electrolyte formulations No. 1-34.

Composition (I)	By weight%
		ZnBr₂	34.90
Water (W)	39.00
		KBr	12.23
KCl	2.18
		1-Ethyl-4-methylpyridinium bromide	4.07
Acetic acid	0.48
		Triethyl methyl ammonium chloride	5.01
mPEG-2K	1.64
		mPEG-1K	0.41
1, 1-dioctadecyl-4, 4' -bipyridinium dibromide	0.11
		Cetyl trimethyl ammonium Bromide	0.08
Totaling:	about 100.00

Table 35: electrolyte formulations No. 1-35.

In said example 1, electrolytes containing various quaternary ammonium agents of the present invention were tested to evaluate the effect of the quaternary ammonium agent on the power and stability of zinc-bromine electrochemical cells. Figure 32 shows typical ranges of power and stability observed for most of the tested quats and classifies them as ammonium complexing agents, pyridinium or pyrrolidinium complexing agents, or imidazolium complexing agents. Stable electrolytes, i.e. exposure to Br at 60 ℃₂After 7 days, the pH value is shown to be lowerA small variation of the electrolyte is desirable. With faster Br₂A dynamic electrolyte, i.e., an electrolyte with greater maximum power at the tafel limit current for Br reduction, can make the cell more powerful and also desirable.

Experiment of pH stability

In said example 1, a stability experiment was performed on each of the above electrolytes to determine whether the ingredients in the electrolyte formulation were stable or when exposed to Br at 60 ℃₂Whether or not a significant change in pH was exhibited over a period of 7 days.

In the above formulation, ZnBr₂Deionized water (di water), KBr and KCl were added to a 500mL flask and stirred until all the salts had dissolved (about 30 minutes). Acetic acid was then added followed by stirring for about 5 minutes, followed by the addition of the crown ether (when present), DME-PEG (when present), and any other organic components. Followed by the addition of a quaternary ammonium agent, followed by mixing tin chloride dihydrate (when present) and indium-nitric acid solution (when present) into the formulation. Finally, concentrated HBr acid was added to each of the above formulations to adjust the pH to approximately 3.

200 grams of electrolyte was placed in an amber bottle. Amber bottles were used to protect the light sensitive bromine from light. The pH of the electrolyte was measured. 3.75 grams of bromine was added to the electrolyte, the amber bottle was capped tightly, and the resulting mixture was carefully shaken for at least 20 seconds.

The pH of the bromine-doped electrolyte was then taken after shaking the bottle. Next, a piece of parafilm was wrapped around the top/lid of the amber bottle after closing the lid to make it airtight, and the spiked electrolyte was placed in an oven at 60 ℃ for 7 days. After a period of 7 days, the pH of the spiked electrolyte was measured (after cooling to room temperature) to evaluate the effect of bromine on the composition of the electrolyte. After measuring and recording the pH of the solution for up to one week, it needs to be re-capped and re-wrapped with parafilm and has to be placed in the oven again. An electrolyte formulation is characterized as stable if its initial pH does not change by more than a value of about 1.0 after being spiked with bromine and subjected to elevated temperatures for a period of 7 days.

Power experiment

Each of the bromine-doped electrolytes was added to a three-necked round bottom flask. A glassy carbon working electrode was added to the first neck of the flask, a zinc metal counter electrode was added to the second neck of the flask, and a saturated mercurous chloride reference electrode was added to the third neck of the flask. All electrodes were immersed in spiked electrolyte in the flask. Linear Sweep Voltammetry (LSV) experiments were performed with respect to a saturated mercurous chloride electrode, where the potential was swept from 1.3V to 0.4V. The voltage was scanned at a rate of 1 mV/s. Generated for Br^-Oxidation and Br₂The reduced current is measured as a function of the voltage.

By directing at Br₂The limiting current of the reduction multiplied by the highest voltage obtained at the limiting current is calculated at Br₂Maximum power obtained during reduction. For Br over a saturated mercurous chloride electrode₂The maximum power of reduction usually reaches around 0.4V.

The results of the stability experiment and the power experiment are provided in fig. 32 to 34.

Example 1B-electrochemical cell comprising the electrolyte formulation of example 1A

Referring to fig. 35-38, selected electrolytes formulated as described in example 1A above were added to dry electrochemical test cells, which were evaluated for discharge capacity, coulombic efficiency, run time, and energy efficiency as a function of the number of charge cycles. The unit cell used in the example was formed as shown in fig. 1. Each test cell contained a Calgon Carbon Zorflex ACC FM-10 Carbon cloth separator cut into rectangles (width about 5.31cm, length about 12.076cm) using a ruled surface die coated in ZrN of the same shape. The carbon material was formulated with 20kg of PTFE dispersion (60 wt%) (DuPont DISP30 PTFE dispersion), 10kg of Cabot PBX52 carbon black, 1kg of carbon fiber (3mm), 10kg of akknobel (Akzo-Nobel) Ketjenblack EC600JD carbon black, and 10kg of deionized water. The dry ingredients were pre-mixed in a 55 gallon drum with an antistatic drum liner to form a relatively homogeneous mixture, the PTFE dispersion and deionization were added to the mixture, and the resulting mixture was stirred to produce a dough-like material. The dough material was formed into pieces (about 5.24cm in length, about 3.94cm in width, and about 3.7mm in thickness) and oven dried to remove moisture to form a block of carbon material. Three such blocks were added to the cathode holder in the test cell. The electrode plate and terminal plate were formed from TiC coated Titanium metal (commercially available from Titanium Metals Corporation, Exton, PA) and formed into a plate (length about 13.5cm, width about 8.375cm, thickness about 0.005cm) with 45 ° chamfered corners. The cathode holder was stamped to have a reduced surface area of pocket portions (length about 5.187cm, width about 11.952cm), and a total length of about 5.73cm and a total width of about 12.495cm, and a pocket depth of about 0.157cm were obtained from the width of the cathode holder from the peripheral edge of one flange to the peripheral edge of the opposite flange. The adjusted hole pattern is chemically etched into the reduced surface area of the pocket portion of the cathode holder with an acid, wherein centers of adjacent holes along a row are spaced apart by about 0.065cm in the x-direction and each other row is spaced apart by about 0.152cm in the y-direction. The cathode holder was loaded with separator and 3 pieces of carbon material to form a cathode assembly that was laser welded to the electrode plate with an offset of about 0.694cm from the bottom edge of the electrode plate and an offset of about 0.502cm from each side edge of the electrode plate. The cathode assembly was laser welded to the electrode plate along the flange of the cathode holder. On the surface of the bipolar electrode plate opposite the cathode assembly, an electrically conductive cup-shaped member is laser welded such that the center of the cup-shaped member is approximately aligned or centered with the center of the reduced surface of the cathode holder. The component thus serves as the terminal cathode assembly and bipolar electrode of the test cell. The terminal anode assembly is similarly formed from a terminal end plate having substantially the same dimensions as the dimensions of the bipolar electrode plate, with an oval cup-shaped member laser welded to the outer surface of the terminal anode end plate such that the center of the cup-shaped member is approximately collinear with the center of the cup-shaped member of the terminal cathode assembly. The conductive cup-shaped member is formed from a stamped titanium carbide material. The test cells were finally assembled by inserting a single high density polyethylene frame member having the sealing ring secured therein between the terminal anode assembly and the terminal cathode assembly and compressing the components between two opposing 6061-T6 aluminum press plates. The dry test cells were constructed using the selected electrolytes described above and loaded to capacity. For these experiments, a control electrolyte No. 1 as described in example 2 was used in a control electrochemical cell.

During battery cycling, the battery was charged to a capacity of 750mAh and at 20mA/cm²And discharging. The results of the test are provided in fig. 35 to 38.

Example 2: electrolyte formulation No. 2-1

Bipolar static (no-flow) battery test:

the following electrolyte formulations were tested in the batteries shown in fig. 18 to 20.

Each of the 28 bipolar electrodes of the battery comprised a Calgon Carbon Zorflex ACC FM-10 Carbon cloth separator cut into rectangles (width about 5.31cm, length about 12.076cm) using a ruled surface die coated in ZrN of the same shape. The carbon material was formulated with 20kg of PTFE dispersion (60 wt%) (DuPont DISP30 PTFE dispersion), 10kg of Cabot PBX52 carbon black, 1kg of carbon fiber (3mm), 10kg of akknobel (Akzo-Nobel) Ketjenblack EC600JD carbon black, and 10kg of deionized water. The dry ingredients were pre-mixed in a 55 gallon drum with an antistatic drum liner to form a relatively homogeneous mixture, the PTFE dispersion and deionization were added to the mixture, and the resulting mixture was stirred to produce a dough-like material. The dough material was formed into pieces (about 5.24cm in length, about 3.94cm in width, and about 3.7mm in thickness) and oven dried to remove moisture to form a block of carbon material. Three such pieces were added to the cathode holder in the test cell. The bipolar electrode plate was formed of TiC coated Titanium metal (commercially available from Titanium Metals Corporation, Exton, PA) and formed into a plate (length about 13.5cm, width about 8.375cm, thickness about 0.005cm) with 45 ° chamfered corners. The cathode holder was stamped to have a reduced surface area of pocket portions (length about 5.187cm, width about 11.952cm), and a total length of about 5.73cm and a total width of about 12.495cm, and a pocket depth of about 0.157cm were obtained from the width of the cathode holder from the peripheral edge of one flange to the peripheral edge of the opposite flange. The adjusted hole pattern is chemically etched into the reduced surface area of the pocket portion of the cathode holder with an acid, wherein centers of adjacent holes along a row are spaced about 0.065cm apart in the x-direction and each other row is spaced about 0.152cm apart in the y-direction. The cathode holder was loaded with separator and 3 pieces of carbon material to form a cathode assembly that was laser welded to the electrode plate with an offset of about 0.694cm from the bottom edge of the electrode plate and an offset of about 0.502cm from each side edge of the electrode plate. The cathode assembly was laser welded to the electrode plate along the flange of the cathode holder.

The terminal cathode assembly is formed by laser welding an electrically conductive cup-shaped member onto a bipolar electrode as described above on the side opposite the cathode assembly such that the center of the cup-shaped member is approximately aligned or centered with the center of the reduced surface of the cathode assembly. The terminal anode assembly is similarly formed from a terminal end plate having substantially the same dimensions as the dimensions of the bipolar electrode plate, with an oval cup-shaped member laser welded to the outer surface of the terminal anode end plate such that the center of the cup-shaped member is approximately collinear with the center of the cup-shaped member of the terminal cathode assembly. The conductive cup-shaped member is formed from a stamped titanium carbide material. A portion of the inner surface of the terminal anode end plate corresponding to the reduced surface of the opposing cathode assembly of the terminal cathode assembly is grit blasted to provide a roughened surface. The test battery pack was assembled by inserting a high density polyethylene frame member between 1) the cathode terminal end plate and the bipolar electrode, 2) each of the bipolar electrodes, and 3) the terminal anode end plate and the bipolar electrode, thereby requiring a total of 30 frame members. Each of the 30 frame members has a sealing ring on a first surface thereof and a sealing ring on a second surface thereof. Two opposing 6061-T6 aluminum platens are pressed against the adjacent components using tie rods and fasteners as shown in fig. 18-20 to compress the 30 frame members. The dry battery is constructed using the electrolyte described below and loaded to a capacity.

No. 1 control electrolyte

The formulation of control electrolyte No. 1 was based on the formulation described in U.S. patent No. 4,482,614. Control electrolyte No. 1 was formulated as follows:

table 36: formulation of control electrolyte No. 1

Composition (I)	Quantity of	Weight percent
			ZnBr₂	675g	67.5
NH₄Cl	100g	10
			PEG	15g	1.5
Water (I)	210g	21
			Totaling:	1000g	100

no. 2 control electrolyte

The formulation of control electrolyte No. 2 was based on the formulations described by Yan (Yan, Jung Hoon), Yan sheng (Yan, Hyeon Sun), la jon (Ra, Ho Won), and others. Effect of surfactants on the performance of zinc/bromine redox flow batteries: improvements in current efficiency and system stability, 275(2015)294 (J for Power Sources) 297. Control electrolyte No. 2 was formulated as follows:

table 37: formulation of control electrolyte No. 2.

Composition (I)	Measurement of	By weight%
			ZnBr₂	507g	50.7
ZnCl₂	68g	6.8
			N-methyl-N-ethylpyrrolidinium bromide	155g	15.5
Water (W)	270g	27
			Totaling:	1000g	100

electrolyte formulation 2-1

The electrolyte of the present invention was prepared as follows:

table 38: test electrolyte formulations No. 2-1.

Composition (I)	Measurement of
		ZnBr₂	345g
KBr	85.2g
		KCl	81.2g
Tetraglyme	32.5g
		DME-PEG 2000	16.2g
Tetraethyl ammonium bromide	25.5g
		MEMBr	8.5g
Neopentyl glycol	16.2g
		Tert-butyl alcohol	4.1g
Water (W)	385g
		SnCl₂·2H₂O	10ppm
In	10ppm

The pH of the electrolyte was adjusted to 3 using concentrated HBr.

For these tests, each electrolyte was loaded into two test batteries to provide duplicate test data (i.e., n-2). Each of the test packs was initially charged at a constant voltage of 38.0V and terminated at 15 minutes or less than 100 mA. Charging continued at a constant current of +7.16Amp and terminated at 58.5V or 30Ah total accumulated charge. The cell was discharged at a constant current of-8.0A and terminated at 33V.

As a result:

referring to fig. 28, 29A, and 29B, plots of battery energy (in watts) as a function of number of charge cycles indicate that the test battery using the test electrolyte maintained greater charge and discharge energy after more charge cycles than any of the control electrolytes. Also, the plot of battery capacity (in amps) as a function of the number of charge cycles indicates that the test battery using electrolyte formulation No. 2-1 retained a greater charge capacity after more charge cycles than either of the control electrolytes.

Example 3: cathode holder hole pattern

Negative control-two dry test cells were formed as described in example 1B, but the cathode holder in both cells had a series of unadjusted holes in the pocket portion of the cathode holder. The dry test cell was loaded to capacity and charged using No. 1 control electrolyte.

Test cells-three dry test cells were formed as described in example 1B, which contained an adjusted hole pattern on the reduced surface of the pocket portion of the cathode holder. The dry test cells were loaded to capacity and charged using No. 1 control electrolyte.

Referring to fig. 30A to 31C, after charging, the test cell was deconstructed and the zinc plating on the anode surface of the cell was evaluated. Fig. 30A and 30B show zinc plating in the negative control test cell and fig. 31A to 31C show zinc plating on the test cell. Fig. 30A to 31C illustrate that enhanced zinc plating was observed for test cells formed from cathode holders having a pattern of conditioning holes on their respective pocket areas. As shown in fig. 30A and 30B, zinc metal is deposited in an irregular pattern when the corresponding cathode holder has a series of unadjusted holes. In contrast, and as shown in fig. 31A, 31B and 31C, zinc metal is deposited in a more regular and complete pattern when the corresponding cathode holder has a series of adjusted holes.

Example 4: battery performance

Referring to fig. 24, 25A, 25B, 26, 27A, and 27B, the test battery pack as described in example 1 was subjected to charge/discharge cycles to evaluate the performance characteristics of the test battery pack. The data from the tests are plotted in the figure referenced in this example 3.

Example 5: alkyl ammonium bromides in electrolytes

The following electrolytes were formulated as follows:

table 39: electrolyte formulation No. 5-1.

Composition (I)	Quantity (g)	Weight percent
			ZnBr
₂	85	34.71
			Water (W)	95	38.79
KBr	21	8.57
			KCl	20	8.17
Acetic acid	1.11	0.45
			1-Ethyl-2-methylpyridinium bromide	9.92	4.05
Chloroethyl ammonium chloride	12.2	4.98
			18-crown-6	0.55	0.22
Cetyl trimethyl ammonium Bromide	0.1	0.04
			SnCl₂·2H₂O	About 0.0047	About 0.0019
In (In nitric acid solution)	About 0.0025	About 0.0010
			Nitric acid (from solution)	About 0.026	About 0.0106
Totaling:	about 244.91	About 100.00

Table 40: electrolyte formulation No. 5-2.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.73
			Water (W)	95	38.82
KBr	21	8.58
			KCl	20	8.17
Acetic acid	1.11	0.45
			1-Ethyl-4-methylpyridinium bromide	9.92	4.05
Tetraethyl ammonium bromide	6.0	2.45
			Trimethylpropylammonium bromide	6.0	2.45
18-crown-6	0.55	0.22
			Cetyl trimethyl ammonium Bromide	0.1	0.04
SnCl₂·2H₂O	About 0.0047	About 0.0019
			In (In nitric acid solution)	About 0.0025	About 0.0010
Nitric acid (from solution)	About 0.026	About 0.0106
			Totaling:	about 244.71	About 100.00

Table 41: electrolyte formulations No. 5-3.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.73
			Water (W)	95	38.82
KBr	21	8.58
			KCl	20	8.17
Acetic acid	1.11	0.45
			1-Ethyl-4-methylpyridinium bromide	9.92	4.05
Tetraethyl ammonium bromide	6.0	2.45
			Triethyl methyl ammonium Bromide	6.0	2.45
18-crown-6	0.55	0.22
			Cetyl trimethyl ammonium Bromide	0.1	0.04
SnCl₂·2H₂O	About 0.0047	About 0.0019
			In (In nitric acid solution)	About 0.0025	About 0.0010
Nitric acid (from solution)	About 0.026	About 0.0106
			Totaling:	about 244.71	About 100.00

Table 42: electrolyte formulation No. 5-4

Table 43: electrolyte formulations No. 5-5.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.73
			Water (W)	95	38.82
KBr	21	8.58
			KCl	20	8.17
Acetic Acid (AA)	1.11	0.45
			1-Ethyl-4-methylpyridinium bromide	9.92	4.05
Tetraethyl ammonium bromide	6.0	2.45
			triethyl-N-methoxymethylammonium bromide	6.0	2.45
18-crown-6	0.55	0.22
			Hexadecyl trimethyl ammonium bromide	0.1	0.04
SnCl₂·2H₂O	About 0.0047	About 0.0019
			In (In nitric acid solution)	About 0.0025	About 0.0010
Nitric acid (from solution)	About 0.026	About 0.0106
			Totaling:	about 244.71	About 100.00

Each of the electrolytes in the examples was loaded into the dry battery pack described in example 2.

Each of the test packs was initially charged at a constant voltage of 38.0V and terminated at 15 minutes or less than 100 mA. Charging at +17.9mA/cm²Continues at 58.5V or ends at a total accumulated charge of 30 Ah. The battery was allowed to stand at-20.0 mA/cm²The discharge was terminated at 33V.

A plot of cyclic voltammetry measurements for each of the test battery packs is provided in fig. 39.

Example 6A:

triethylmethylammonium bromide was evaluated as a replacement for tetraethylammonium bromide in the electrolyte formulation using electrolytes No. 1-32. Accordingly, electrolytes No. 1 to 32 were evaluated as described below.

During the preparation of electrolytes nos. 1-32, it has been noted that triethylmethylammonium bromide exhibits a surprisingly significant increase in solubility over tetraethylammonium bromide.

140mA/cm shown in FIGS. 40 to 43²Electrolytes No. 1-32 were evaluated in the test cells. These test cells are formed by a housing 600 that includes a reaction chamber 610 formed therein. Two slotted teflon inserts 620, 630 are disposed within the reaction chamber at opposite sides such that the slots of the inserts face inward and are co-aligned with each other. Two L-shaped titanium

current collector plates

640, 650, coated with titanium carbide or heat-injected with carbon, are mounted into the slotted insert such that one

leg

660a, 660b of each L-shaped current collector plate is oriented vertically and the

other leg

670a, 670b is oriented horizontally and facing outward at the top of the reaction chamber, thereby forming an electrolyte reservoir 680 with the slotted insert. Accordingly, the electrolyte reservoir is defined by two opposing side walls formed by the vertically oriented faces of the current collectors, two opposing side walls formed by the slotted inserts, and a bottom formed by the bottom of the reaction chamber. A carbon felt (Avcarb G150)690 is bonded to the vertically oriented leg 660b of the L-shaped current collector plate 650 facing the electrolyte reservoir. The test cell also included a teflon cover 700 with a pressure relief valve 710 and two through

holes

720, 730 through which the electrodes were placed in electrical contact with the horizontally oriented legs of the current collector plate.

Referring to fig. 44, during the test, the volume of electrolyte No. 1-32 was kept constant (20 mL total), while battery performance was evaluated at electrolyte depths of 6mm (cells 9182 and 9183) and 8mm (cells 9184 and 9185). The variation in electrolyte depth is adjusted by moving the L-shaped current collector plates to different slots thereby narrowing the gap between the opposing vertical faces of the current collector plates.

Each test was performed repeatedly (n ═ 2)

Referring to fig. 44, the energy efficiency and coulombic efficiency of the test cell were evaluated over five cycles. The average energy efficiency of test cells 9182 and 9183 was calculated to be 71.2%, the average energy efficiency of test cells 9184 and 9185 was calculated to be 69.7%, the average coulombic efficiency of test cells 9182 and 9183 was calculated to be 92.5%, and the average coulombic efficiency of test cells 9184 and 9185 was calculated to be 93.1%. Accordingly, when the current is 140mA/cm²Electrolytes No. 1-32 exhibited high coulombic and energy efficiencies when used in the test cells for charge capacity.

Example 6B:

table 44: electrolyte formulation No. 6-1.

Composition (I)	Quantity (g)	By weight%
			ZnBr
₂	85	34.92
			Water (W)	95	39.03
KBr	5.3	2.18
			KCl	29.8	12.24
Acetic acid	1.11	0.46
			1-Ethyl-4-methylpyridinium bromide	9.92	4.08
Tetraethyl ammonium bromide	12.2	5.01
			DME-PEG 2000	4	1.64
DME-PEG 1000	1	0.41
			Cetyl trimethyl ammonium Bromide	0.1	0.04
Totaling:	about 243.43	About 100.00

140mA/cm as described in example 6A²The energy efficiency and coulombic efficiency of electrolyte No. 6-1 was evaluated in the test cell (cell 9084) and compared to the test results from the corresponding cell with electrolyte No. 1-32 (cell 8084).

Referring to fig. 45, the energy efficiency and coulombic efficiency of the test cells were evaluated over 25 cycles. Coulombic efficiency and energy of 9084 batteryThe efficiency is significantly greater than the coulombic and energy efficiency of battery 8084. Accordingly, when the current is 140mA/cm²The No. 6-1 electrolyte exhibited excellent coulombic and energy efficiencies when used in a test cell for charge capacity.

Example 6B:

the electrolyte No. 6-2 was prepared as follows:

table 45: electrolyte formulation No. 6-2.

Composition (I)	Quantity (g)	Weight percent
			ZnBr
₂	85	34.92
			Water (W)	95	39.03
KBr	5.3	2.18
			KCl	29.8	12.24
Acetic acid	1.11	0.46
			1-Ethyl-3-methylpyridinium bromide	9.92	4.08
Tetraethyl ammonium bromide	12.2	5.01
			DME-PEG 2000	4	1.64
DME-PEG 1000	1	0.41
			Cetyl trimethyl ammonium Bromide	0.1	0.04
Totaling:	about 243.43	About 100.00

Referring to fig. 46, test cells as described above in example 6A were subjected to cyclic voltammetry tests as described in example 5, with one test cell configured with electrolyte No. 1-32, one test cell configured with electrolyte No. 6-1, and one test cell configured with electrolyte No. 6-2.

Example 7:

the following electrolyte formulations were prepared and evaluated in test cells as described above in example 6A.

Table 46: electrolyte formulation No. 7-1.

Table 47: electrolyte formulations No. 7-2.

Composition (I)	By weight%
		ZnBr₂	26.56
H₂O	48.82
		KBr	6.56
KCl	10.97
		Methyl Ethyl morpholinium Bromide	0.99
Tetraethyl ammonium bromide	1.97
		Triethyl methyl ammonium chloride	1.88
MPEG 2K	1.25
		MPEG 1K	0.31
HBr	0.52
		1, 1-dioctadecyl-4, 4' -bipyridinium dibromide	0.11
Hexadecyl trimethyl ammonium bromide	0.06
		Sn	7ppm
In	7ppm
		Totaling:	about 100.00

Table 48: electrolyte formulations No. 7-3.

Composition (I)	By weight%
		ZnBr₂	28.67
H₂O	46.35
		KBr	7.09
KCl	10.28
		Methyl Ethyl morpholinium Bromide	1.08
Tetraethyl ammonium bromide	2.12
		Triethyl methyl ammonium chloride	2.03
MPEG 2K	1.35
		MPEG 1K	0.33
HBr	0.52
		1, 1-dioctadecyl-4, 4' -bipyridinium dibromide	0.11
Cetyl trimethyl ammonium Bromide	0.06
		Sn	7ppm
In	7ppm
		Totaling:	about 100.00

Each of the test cells produced using electrolyte nos. 7-1, 7-2, or 7-3 showed an energy efficiency of greater than 80%.

Example 8:

referring to fig. 47-52, electrolyte formulations were prepared and evaluated in test cells configured as described in fig. 1, wherein the terminal cathode plate was formed of 0.020 inch thick TiC plate with 6.4mm thick carbon felt (G250) in a test cell

) Adhered to the active area of the TiC board (activated) with a binder consisting of 60 wt% acetone, 13.92 wt% polyvinylidene fluoride resin(s) (activated)

2750-00), 7.52 wt% of isobutyl methacrylate resin (

4111) 16.16% by weight of artificial graphite (b)

KS6), 2 wt% sodium hexametaphosphate, and 0.4 wt% polymethyl methacrylate (PMMA). The frame member is formed from machined HDPE. The cell was repeatedly cycled under the following conditions, namely: at constant power of 2.25W and ramping up to 5.5W, charge potential of 1.95V, charge capacity cut-off of 7.5Ah and ramping up to 15Ah, maximum charge rest time 30 minutes and ramping up to 24 hours, discharge current at constant power of 2.25W and ramping up to 5.5W, discharge voltage 1.1V, minimum discharge rest time 6 hours, and test temperature ambient temperature.

Table 49: electrolyte formulation No. 8-1.

Composition (A)	Weight percent
		ZnBr₂	40.89
H₂O	35.64
		KBr	4.95
KCl	10.01
		Triethyl methyl ammonium chloride	5.25
Tetraethyl ammonium bromide	0.99
		MPEG 2K	1.14
MPEG 1K	0.32
		Neopentyl glycol	0.90
InCl₃	7ppm
		SnCl₂·2H₂O	7ppm
HBr	Adjusting to pH 3
		Totaling:	about 100.00

Table 50: electrolyte formulation No. 8-2.

Table 51: electrolyte formulation No. 8-3

Composition (I)	By weight%
		ZnBr₂	38.65
H₂O	34.22
		KBr	7.09
KCl	11.81
		Triethyl methyl ammonium chloride	5.01
Tetraethyl ammonium bromide	0.95
		MPEG 2K	1.08
MPEG 1K	0.30
		Neopentyl glycol	0.86
InCl₃	7ppm
		SnCl₂·2H₂O	7ppm
HBr	Adjusting to pH 3
		Totaling:	about 100.00

Table 52: electrolyte formulation No. 8-4.

Composition (I)	By weight%
		ZnBr₂	39.29
H₂O	34.78
		KBr	4.80
KCl	9.70
		Triethyl methyl ammonium chloride	6.72
Tetraethyl ammonium bromide	2.40
		MPEG 2K	1.10
MPEG 1K	0.31
		Neopentyl glycol	0.87
InCl₃	7ppm
		SnCl₂·2H₂O	7ppm
HBr	Adjusting to pH 3
		Totaling:	about 100.00

Table 53: electrolyte formulations No. 8-5.

Table 54: electrolyte formulations No. 8-6.

Composition (I)	By weight%
		ZnBr₂	39.98
H₂O	35.39
		KBr	4.88
KCl	9.87
		Triethyl methyl ammonium chloride	5.18
Tetraethyl ammonium bromide	0.97
		MPEG 2K	1.12
MPEG 1K	0.31
		Neopentyl glycol	2.25
InCl₃	7ppm
		SnCl₂·2H₂O	7ppm
HBr	Adjusting to pH 3
		Totaling:	about 100.00

Table 55: electrolyte formulations nos. 8-7.

Composition (I)	Weight percent
		ZnBr₂	40.41
H₂O	35.78
		KBr	4.94
KCl	9.98
		Triethyl methyl ammonium chloride	5.23
Tetraethyl ammonium bromide	0.98
		MPEG 2K	1.13
MPEG 1K	0.31
		Neopentyl glycol	0.98
Tetraglyme	0.29
		InCl₃	7ppm
SnCl₂·2H₂O	7ppm
		HBr	Adjusting to pH 3
Totaling:	about 100.00

Example 9:

referring to fig. 53-58, electrolyte formulations were prepared and evaluated in test cells configured as described in fig. 1, wherein the terminal cathode plate was formed from a 0.020 inch thick TiC plate with a 6.4mm thick carbon felt (G250) of

2750-00), 7.52 wt% of isobutyl methacrylate resin (

4111) 16.16% by weight of artificial graphite (b)

KS6), 2% by weight of sodium hexametaphosphate and 0.4% by weight of polymethyl methacrylate (PMMA). The frame member is formed from machined HDPE. The cell was repeatedly cycled under the following conditions, namely: at constant power of 2.25W and ramping up to 5.5W, charge potential of 1.95V, charge capacity cut-off of 7.5Ah and ramping up to 15Ah, maximum charge rest time 30 minutes and ramping up to 24 hours, discharge current at constant power of 2.25W and ramping up to 5.5W, discharge voltage 1.1V, minimum discharge rest time 6 hours, and test temperature ambient temperature.

Table 56: electrolyte formulation No. 9-1.

Composition (I)	By weight%
		ZnBr₂	42.07
H₂O	27.23
		KBr	6.28
KCl	10.52
		Triethyl methyl ammonium chloride	8.33
Tetraethyl ammonium bromide	2.98
		MPEG 2K	1.06
MPEG 1K	0.30
		Neopentyl glycol	0.84
InCl₃	7 ppm
		SnCl₂·2H₂O	7 ppm
HBr	Adjusting to pH 3
		Totaling:	about 100.00

Table 57: electrolyte formulation No. 9-2.

Composition (I)	By weight%
		ZnBr₂	42.07
H₂O	27.23
		KBr	3.01
KCl	13.84
		Triethyl methyl ammonium chloride	8.33
Tetraethyl ammonium bromide	2.98
		MPEG 2K	1.06
MPEG 1K	0.30
		Neopentyl glycol	0.84
InCl₃	7 ppm
		SnCl₂·2H₂O	7 ppm
HBr	Adjusting to pH 3
		Totaling:	about 100.00

Table 58: electrolyte formulation No. 9-3.

Composition (I)	By weight%
		ZnBr₂	42.07
H₂O	27.23
		KBr	8.20
KCl	8.31
		Triethyl methyl ammonium chloride	8.33
Tetraethyl ammonium bromide	2.98
		MPEG 2K	1.06
MPEG 1K	0.30
		Neopentyl glycol	0.84
InCl₃	7ppm
		SnCl₂·2H₂O	7ppm
HBr	Adjusting to pH 3
		Totaling:	about 100.00

Table 59: electrolyte formulation No. 9-4.

Composition (A)	Weight percent
		ZnBr₂	42.07
H₂O	27.23
		KBr	6.28
KCl	10.52
		Triethyl methyl ammonium chloride	8.33
Trimethylpropylammonium bromide	0.40
		Tetraethyl ammonium bromide	2.48
MPEG 2K	1.06
		MPEG 1K	0.30
Neopentyl glycol	0.84
		InCl₃	7ppm
SnCl₂·2H₂O	7ppm
		HBr	Adjusting to pH 3
Totaling:	about 100.00

Example 10:

referring to fig. 59-64, electrolyte formulations were prepared and evaluated in test cells configured as described in fig. 1, wherein the terminal cathode plate was formed of 0.020 inch thick TiC plate with 6.4mm thick carbon felt (G250) in a test cell

2750-00), 7.52 wt% of isobutyl methacrylate resin (

4111) 16.16% by weight of artificial graphite (b)

KS6), 2% by weight of sodium hexametaphosphate and 0.4% by weight of polymethyl methacrylate (PMMA). The frame member is formed from machined HDPE. The cell was repeatedly cycled under the following conditions, namely: at a constant power of 2.25W and ramp up to5.5W, a charge potential of 1.95V, a charge capacity cut off at 7.5Ah and ramped up to 15Ah, a maximum charge rest time of 30 minutes and ramped up to 24 hours, a discharge current of constant power of 2.25W and ramped up to 5.5W, a discharge voltage of 1.1V, a minimum discharge rest time of 6 hours, and a test temperature of ambient temperature.

Table 60: electrolyte formulation No. 10-1.

Composition (A)	By weight%
		ZnBr₂	43.10
H₂O	25.64
		KBr	4.58
KCl	9.05
		Triethyl methyl ammonium chloride	12.11
Tetraethyl ammonium bromide	2.73
		Trimethylpropylammonium bromide	0.50
MPEG 2K	1.18
		MPEG 1K	0.35
Neopentyl glycol	0.71
		InCl₃	7ppm
SnCl₂·2H₂O	7ppm
		HBr	Adjusting to pH 3
Totaling:	about 100.00

Table 60: electrolyte formulation No. 10-2.

Composition (A)	By weight%
		ZnBr₂	42.75
H₂O	29.31
		KBr	4.55
KCl	9.09
		Triethyl methyl ammonium chloride	9.00
Tetraethyl ammonium bromide	2.00
		Trimethylpropylammonium bromide	0.53
MPEG 2K	1.18
		MPEG 1K	0.36
Neopentyl glycol	0.73
		InCl₃	7ppm
SnCl₂·2H₂O	7ppm
		HBr	Adjusting to pH 3
Totaling:	about 100.00

Table 61: electrolyte formulation No. 10-3.

Table 62: electrolyte formulation No. 10-4.

Composition (I)	By weight%
		ZnBr₂	42.75
H₂O	28.11
		KBr	3.00
KCl	8.00
		Triethyl methyl ammonium chloride	12.60
Tetraethyl ammonium bromide	2.73
		Trimethylpropylammonium bromide	0.53
MPEG 2K	1.18
		MPEG 1K	0.36
Neopentyl glycol	0.73
		InCl₃	7ppm
SnCl₂·2H₂O	7ppm
		HBr	Adjusting to pH 3
Totaling:	about 100.00

Table 63: electrolyte formulation No. 10-5.

Example 11:

electrolyte 11-1 was configured as described in table 64:

table 64: electrolyte formulation No. 11-1.

Composition (I)	By weight%
		ZnBr₂	39.00
H₂O	34.49
		KBr	4.75
KCl	9.62
		Triethyl methyl ammonium chloride	6.66
Tetraethyl ammonium bromide	2.38
		MPEG 2K	1.09
MPEG 1K	0.30
		Neopentyl glycol	1.49
Tetraglyme	0.25
		InCl₃	7ppm
SnCl₂·2H₂O	7ppm
		HBr	Adjusting to pH 3
Totaling:	about 100.00

Other embodiments

It should be apparent that the foregoing relates only to the preferred embodiments of the present invention and that numerous changes and modifications may be made herein without departing from the spirit and scope of the invention as defined by the following claims and the equivalents thereof.

Claims

1. An electrolyte for use in a bipolar, static secondary zinc-bromine electrochemical cell comprising:

25 to 70 wt% ZnBr₂；

5 to 50 wt% water;

0.5 to 5% by weight of C_2-10A diol; and

one or more quaternary ammonium agents in combination with one or more quaternary ammonium agents,

wherein the electrolyte comprises from 0.05 wt% to 10 wt% of the one or more quaternary ammonium agents.

2. The electrolyte of claim 1, further comprising:

1 to 15 wt% KBr;

5 to 20% by weight of KCl.

3. The electrolyte of claim 1 or 2, further comprising 1.5 to 7.5 wt%ZnCl (2)₂。

4. The electrolyte of claim 1 or 2, comprising 30 to 45 wt% water, or optionally comprising 35 to 41 wt% water.

5. The electrolyte of claim 1 or 2, further comprising 0.5 to 10 wt% glyme.

6. The electrolyte of claim 5, wherein the glyme comprises monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or any combination thereof.

7. The electrolyte of claim 1 or 2, comprising 0.5 to 2.5 wt% of an ether selected from DME-PEG, dimethyl ether, or any combination thereof.

8. The electrolyte of claim 7, wherein the electrolyte comprises DME-PEG, and (i) the DME-PEG has a number average molecular weight of 350amu to 3000amu, (ii) the DME-PEG has a number average molecular weight of 1200amu to 3000amu, or any combination thereof.

9. The electrolyte of claim 8, comprising 1 to 2 wt% DME-PEG2000, 0.25 to 0.75 wt% DME-PEG1000, or a combination thereof.

10. The electrolyte of claim 1 or 2, further comprising 0.1 to 1.0 wt.% of an alcohol, wherein the alcohol is substantially miscible in water.

11. The electrolyte of claim 10, wherein the alcohol comprises C_1-4Alcohols, wherein the alcohols optionally comprise methanol, ethanol, 1-propanol, isopropanol, 1-butanol, sec-butanol, isobutanol, isopropanol, butanol, or mixtures thereof,Tert-butanol, or any combination thereof.

12. The electrolyte of claim 1 or 2, wherein the diol comprises ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, hexanediol, or any combination thereof.

13. The electrolyte of claim 1 or 2, wherein the one or more quaternary ammonium agents comprise a quaternary ammonium agent selected from the group consisting of:

tetraethylammonium bromide, trimethylpropylammonium bromide, N-methyl-N-ethylmorpholine bromide (MEMBr), 1-ethyl-1-methylmorpholine bromide, N-methyl-N-butylmorpholine bromide, N-methyl-N-ethylpyrrolidinium bromide, N, N, N-triethyl-N-propylammonium bromide, N-ethyl-N-propylpyrrolidinium bromide, N-propyl-N-butylpyrrolidinium bromide, N-methyl-N-butylpyrrolidinium bromide, 1-methyl-1-butylpyrrolidinium bromide, N-ethyl-N- (2-chloroethyl) pyrrolidinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N-ethylmorpholinium bromide, N-ethyl-N-N-ethylpyrrolidinium bromide, N-ethylmorpholinium bromide, N-methyl-N-ethylpyrrolidinium bromide, N-ethyl-N-ethylpyrrolidinium bromide, N-ethyl-N-ethylpyrrolidinium bromide, N-ethyl-N-pyrrolidinium bromide, N-ethyl-N-ethylpyrroli, N-methyl-N-hexylpyrrolidinium bromide, N-methyl-N-pentylpyrrolidinium bromide, N-ethyl-N-butylpyrrolidinium bromide, trimethylene-bis (N-methylpyrrolidinium) dibromide, N-butyl-N-pentylpyrrolidinium bromide, N-methyl-N-propylpyrrolidinium bromide, N-propyl-N-pentylpyrrolidinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-ethyl-2-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, hexadecyltrimethylammonium bromide, and any combination thereof.

14. The electrolyte of claim 1 or 2, wherein the one or more quaternary ammonium agents comprise

(i)3.5 to 4.5 weight percent 1-ethyl-4-methylpyridinium bromide;

(ii)1 to 7% by weight of 1-ethyl-2-methylpyridinium bromide;

(iii)1.5 to 2.5% by weight of 1-methyl-1-butylpyrrolidinium bromide;

(iv)1.5 to 2.5 weight percent of 1-butyl-3-methylpyridinium bromide;

(v)0.5 to 1.5% by weight of N-methyl-N-ethylmorpholine bromide (MEMBr);

(vi)2 to 3 weight percent trimethylpropylammonium bromide;

(vii)2 to 8 weight percent tetraethylammonium bromide;

(viii)0.05 to 0.2% by weight of cetyltrimethylammonium bromide; or

(ix) Any combination of the above.

15. The electrolyte of claim 1 or 2, further comprising less than 1 wt% of one or more additives, wherein the one or more additives are selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, or Fe, or optionally, the one or more additives are selected from 0.0008 wt% to 0.0012 wt% SnCl₂·H₂O, 0.0008 wt% to 0.0012 wt% In, and combinations thereof.

16. The electrolyte of claim 1 or 2, further comprising an acid or a conjugate base of an acid selected from acetic acid, nitric acid, and citric acid, optionally comprising 0.3 to 0.6 wt.% acetic acid, 0.12 to 0.08 wt.% nitric acid, 3.5 to 4.5 wt.% citric acid, or 3.5 to 4.5 wt.% potassium dihydrogen citrate.

17. The electrolyte of claim 1 or 2, comprising 0.05 to 0.75 wt% of a crown ether, optionally comprising 0.15 to 0.5 wt% of 18-crown-6, 0.05 to 0.2 wt% of 15-crown-5, or any combination thereof.

18. An electrolyte for use in a secondary zinc halide electrochemical cell comprising:

27 to 40 wt% ZnBr by weight of the electrolyte₂；

35 to 41 wt% water;

7.3 to 9.2 wt% KBr;

7 to 17% by weight of KCl;

0.3 to 0.6% by weight of acetic acid; and

2 to 8 weight percent tetraethylammonium bromide.

19. An electrolyte for use in a secondary zinc halide electrochemical cell comprising:

27 to 40 wt% ZnBr by weight of the electrolyte₂；

35 to 41 wt% water;

7.3 to 9.2 wt% KBr;

7 to 17% by weight of KCl;

0.15 to 0.5% by weight of 18-crown-6; and

0.05 to 0.2% by weight of cetyltrimethylammonium bromide.

20. A method of preparing an electrolyte for use in a secondary zinc halide electrochemical cell, comprising:

mixing ZnBr under aqueous conditions₂KBr, KCl and one or more quaternary ammonium agents to produce a mixture and stirring the mixture until the solids have dissolved,

wherein the mixture comprises:

27 to 40 wt% ZnBr₂；

7.3 to 9.2 wt% KBr;

7 to 17% by weight of KCl;

0.05 wt% to 20 wt% of the one or more quaternary ammonium agents; and

35 to 41 wt% water.